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[PATCH] drm/amdgpu: fix recursive ww_mutex acquire in amdgpu_devcoredump_format

by Mikhail Gavrilov

When dumping IB contents from a hung job, amdgpu_devcoredump_format() acquires the VM root PD's reservation lock via amdgpu_vm_lock_by_pasid() and then, for each IB referenced by the job, calls amdgpu_bo_reserve() on the BO that backs the IB. Both reservations are taken on reservation_ww_class_mutex objects but neither uses a ww_acquire_ctx, which trips lockdep: WARNING: possible recursive locking detected -------------------------------------------- kworker/u128:0 is trying to acquire lock: ffff88838b16e1f0 (reservation_ww_class_mutex){+.+.}-{4:4}, at: amdgpu_devcoredump_format+0x1594/0x23f0 [amdgpu] but task is already holding lock: ffff8882f82681f0 (reservation_ww_class_mutex){+.+.}-{4:4}, at: amdgpu_devcoredump_format+0x1594/0x23f0 [amdgpu] Possible unsafe locking scenario: CPU0 ---- lock(reservation_ww_class_mutex); lock(reservation_ww_class_mutex); *** DEADLOCK *** May be due to missing lock nesting notation Workqueue: events_unbound amdgpu_devcoredump_deferred_work [amdgpu] Call Trace: __ww_mutex_lock.constprop.0 ww_mutex_lock amdgpu_bo_reserve amdgpu_devcoredump_format+0x1594 [amdgpu] amdgpu_devcoredump_deferred_work+0xea [amdgpu] process_one_work worker_thread kthread The two reservations are on different BOs in the captured trace, so the splat is a lockdep-correctness warning, not an observed deadlock. It becomes a real self-deadlock whenever the IB BO shares its dma_resv with the root PD (the always-valid case, see amdgpu_vm_is_bo_always_valid()): amdgpu_bo_reserve(abo) re-acquires the same ww_mutex without a ticket and blocks forever. With amdgpu.gpu_recovery=0 the timeout handler refires every ~2 s and each invocation produces this splat, drowning the kernel ring buffer. Fix it by collecting the per-IB BO references under the root PD's reservation, then releasing the root before reserving each IB BO individually. The walk over the VM mapping tree must remain under the root lock (mappings can be torn down without it), but the actual content copies do not need to nest inside it. Each per-IB reservation is now an independent top-level acquire, eliminating the nested ww_mutex. The collect/release logic is factored out into two small helpers (amdgpu_devcoredump_collect_ib_refs / amdgpu_devcoredump_release_ib_refs) to keep the main function's indentation reasonable. This also fixes a BO refcount leak in the original code: when amdgpu_bo_reserve() failed, control jumped to free_ib_content without running amdgpu_bo_unref(). In the new structure the per-IB BO refs are released unconditionally in the cleanup helper. Reproducer (~150 LoC libdrm_amdgpu): submit a single GFX IB containing PACKET3_INDIRECT_BUFFER chained at GPU VA 0 and wait for the fence. The TDR fires within ~10 s and the deferred coredump worker produces the splat above on every invocation. Fixes: 7b15fc2d1f1a ("drm/amdgpu: dump job ibs in the devcoredump") Cc: stable(a)vger.kernel.org # 7.1 Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov(a)gmail.com> --- .../gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c | 147 +++++++++++++----- 1 file changed, 110 insertions(+), 37 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c index d386bc775d03..f6bb968de756 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c @@ -207,6 +207,72 @@ static void amdgpu_devcoredump_fw_info(struct amdgpu_device *adev, } } +struct amdgpu_devcoredump_ib_ref { + struct amdgpu_bo *bo; + u64 offset; +}; + +/* + * Walk the VM's mapping tree under the root PD's reservation to obtain the BO + * that backs each IB and pin it with a refcount. The root PD reservation is + * dropped before this function returns; the caller can then reserve each IB + * BO individually without nesting ww_mutex acquires on + * reservation_ww_class_mutex. + * + * Returns an array of num_ibs entries (each ib_refs[i].bo may be NULL if its + * mapping was not found), or NULL on allocation failure / VM lookup failure. + * The caller must release the BO refs and free the array. + */ +static struct amdgpu_devcoredump_ib_ref * +amdgpu_devcoredump_collect_ib_refs(struct amdgpu_device *adev, + struct amdgpu_coredump_info *coredump) +{ + struct amdgpu_devcoredump_ib_ref *ib_refs; + struct amdgpu_bo_va_mapping *mapping; + struct amdgpu_bo *root; + struct amdgpu_vm *vm; + u64 va_start; + + ib_refs = kcalloc(coredump->num_ibs, sizeof(*ib_refs), GFP_KERNEL); + if (!ib_refs) + return NULL; + + vm = amdgpu_vm_lock_by_pasid(adev, &root, coredump->pasid); + if (!vm) { + kfree(ib_refs); + return NULL; + } + + for (int i = 0; i < coredump->num_ibs; i++) { + va_start = coredump->ibs[i].gpu_addr & AMDGPU_GMC_HOLE_MASK; + mapping = amdgpu_vm_bo_lookup_mapping(vm, va_start / AMDGPU_GPU_PAGE_SIZE); + if (!mapping) + continue; + + ib_refs[i].bo = amdgpu_bo_ref(mapping->bo_va->base.bo); + ib_refs[i].offset = va_start - + mapping->start * AMDGPU_GPU_PAGE_SIZE; + } + + amdgpu_bo_unreserve(root); + amdgpu_bo_unref(&root); + + return ib_refs; +} + +static void +amdgpu_devcoredump_release_ib_refs(struct amdgpu_devcoredump_ib_ref *ib_refs, + int num_ibs) +{ + if (!ib_refs) + return; + + for (int i = 0; i < num_ibs; i++) + if (ib_refs[i].bo) + amdgpu_bo_unref(&ib_refs[i].bo); + kfree(ib_refs); +} + static ssize_t amdgpu_devcoredump_format(char *buffer, size_t count, struct amdgpu_coredump_info *coredump) { @@ -214,13 +280,11 @@ amdgpu_devcoredump_format(char *buffer, size_t count, struct amdgpu_coredump_inf struct drm_printer p; struct drm_print_iterator iter; struct amdgpu_vm_fault_info *fault_info; - struct amdgpu_bo_va_mapping *mapping; struct amdgpu_ip_block *ip_block; struct amdgpu_res_cursor cursor; - struct amdgpu_bo *abo, *root; - uint64_t va_start, offset; + struct amdgpu_bo *abo; + uint64_t offset; struct amdgpu_ring *ring; - struct amdgpu_vm *vm; u32 *ib_content; uint8_t *kptr; int ver, i, j, r; @@ -343,43 +407,52 @@ amdgpu_devcoredump_format(char *buffer, size_t count, struct amdgpu_coredump_inf drm_printf(&p, "VRAM is lost due to GPU reset!\n"); if (coredump->num_ibs) { - /* Don't try to lookup the VM or map the BOs when calculating the - * size required to store the devcoredump. + struct amdgpu_devcoredump_ib_ref *ib_refs = NULL; + + /* + * Snapshot per-IB BO references under the root PD's reservation, + * then release the root before reserving each IB BO individually + * to copy its contents. + * + * Reserving an IB BO while the root PD is still reserved would + * be a nested ww_mutex acquire on reservation_ww_class_mutex + * without a ww_acquire_ctx, which trips lockdep's recursive- + * locking check and self-deadlocks for IB BOs that share their + * dma_resv with the root PD (always-valid BOs). + * + * Skip lookup/reservation entirely on the sizing pass: it does + * not write IB content, and the size estimate doesn't depend on + * whether the BOs are reachable. */ - if (sizing_pass) - vm = NULL; - else - vm = amdgpu_vm_lock_by_pasid(adev, &root, coredump->pasid); + if (!sizing_pass) + ib_refs = amdgpu_devcoredump_collect_ib_refs(adev, coredump); - for (int i = 0; i < coredump->num_ibs && (sizing_pass || vm); i++) { + for (int i = 0; i < coredump->num_ibs; i++) { ib_content = kvmalloc_array(coredump->ibs[i].ib_size_dw, 4, GFP_KERNEL); if (!ib_content) continue; - /* vm=NULL can only happen when 'sizing_pass' is true. Skip to the - * drm_printf() calls (ib_content doesn't need to be initialized - * as its content won't be written anywhere). - */ - if (!vm) + if (sizing_pass) goto output_ib_content; - va_start = coredump->ibs[i].gpu_addr & AMDGPU_GMC_HOLE_MASK; - mapping = amdgpu_vm_bo_lookup_mapping(vm, va_start / AMDGPU_GPU_PAGE_SIZE); - if (!mapping) - goto free_ib_content; + if (!ib_refs || !ib_refs[i].bo) + goto output_ib_content; + + abo = ib_refs[i].bo; + offset = ib_refs[i].offset; - offset = va_start - (mapping->start * AMDGPU_GPU_PAGE_SIZE); - abo = amdgpu_bo_ref(mapping->bo_va->base.bo); r = amdgpu_bo_reserve(abo, false); if (r) - goto free_ib_content; + goto output_ib_content; if (abo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS) { off = 0; - if (abo->tbo.resource->mem_type != TTM_PL_VRAM) - goto unreserve_abo; + if (abo->tbo.resource->mem_type != TTM_PL_VRAM) { + amdgpu_bo_unreserve(abo); + goto output_ib_content; + } amdgpu_res_first(abo->tbo.resource, offset, coredump->ibs[i].ib_size_dw * 4, @@ -395,8 +468,10 @@ amdgpu_devcoredump_format(char *buffer, size_t count, struct amdgpu_coredump_inf r = ttm_bo_kmap(&abo->tbo, 0, PFN_UP(abo->tbo.base.size), &abo->kmap); - if (r) - goto unreserve_abo; + if (r) { + amdgpu_bo_unreserve(abo); + goto output_ib_content; + } kptr = amdgpu_bo_kptr(abo); kptr += offset; @@ -406,21 +481,19 @@ amdgpu_devcoredump_format(char *buffer, size_t count, struct amdgpu_coredump_inf amdgpu_bo_kunmap(abo); } + amdgpu_bo_unreserve(abo); + output_ib_content: drm_printf(&p, "\nIB #%d 0x%llx %d dw\n", i, coredump->ibs[i].gpu_addr, coredump->ibs[i].ib_size_dw); - for (int j = 0; j < coredump->ibs[i].ib_size_dw; j++) - drm_printf(&p, "0x%08x\n", ib_content[j]); -unreserve_abo: - if (vm) - amdgpu_bo_unreserve(abo); -free_ib_content: + if (!sizing_pass && ib_refs && ib_refs[i].bo) { + for (int j = 0; j < coredump->ibs[i].ib_size_dw; j++) + drm_printf(&p, "0x%08x\n", ib_content[j]); + } kvfree(ib_content); } - if (vm) { - amdgpu_bo_unreserve(root); - amdgpu_bo_unref(&root); - } + + amdgpu_devcoredump_release_ib_refs(ib_refs, coredump->num_ibs); } return count - iter.remain; -- 2.54.0

1 month

A Guide to Slither io and the Joy of Simple Gaming

by kaywilson＠wshu.net

In a world filled with hyper-realistic graphics and complex narratives, sometimes the most captivating experiences are the simplest. Enter Slither io, a game that takes the classic "snake" concept and injects it with a healthy dose of online multiplayer mayhem. If you've ever found yourself drawn to the addictive nature of growing a digital creature, or the thrill of outsmarting your opponents in a low-stakes, high-fun environment, then read on. This article will guide you through the basics of Slither io and offer some insights into how to master its charmingly straightforward gameplay. What is Slither io? A Journey into the World of Glowing Serpents Slither io is an online multiplayer arcade game where you control a vibrant, glowing snake. Your objective is deceptively simple: grow your snake by consuming glowing pellets scattered across the map, while avoiding collisions with other players. The twist? Unlike traditional snake games, touching another snake's body (not just its head) means instant demise. This core mechanic creates a dynamic and surprisingly strategic environment where even the smallest snake can take down the largest, given the right timing and tactical positioning. The game's accessibility, with its browser-based play and intuitive controls, makes it a perfect pick-up-and-play experience for anyone looking to unwind and have a little competitive fun. The Dance of the Serpent: Understanding Slither io Gameplay Getting started in Slither io is remarkably easy. Upon loading the game, you'll be prompted to enter a nickname. Once you're in, you'll find yourself as a small, brightly colored snake on a vast, dark arena filled with glowing food. https://slitherio.onl Movement: Your snake follows your mouse cursor. Simply move your mouse to guide your snake in the desired direction. There are no "up, down, left, right" keys – it's all about smooth, continuous movement. Boosting: This is where the strategic element truly shines. By holding down the left mouse button (or spacebar), your snake will accelerate rapidly. While boosting allows you to quickly grab food or outmaneuver opponents, it comes at a cost: your snake will shrink slightly as it consumes a portion of its own mass to fuel the boost. Mastering when and where to boost is crucial for survival and growth. Eating: The primary way to grow your snake is by consuming the colorful pellets scattered across the map. These pellets appear naturally and also drop from deceased snakes. Larger snakes leave behind more food, creating opportunities for smaller snakes to quickly bulk up. Eliminating Opponents: The most satisfying (and often frustrating) part of Slither io is taking down other players. To do this, you need to trick another snake into colliding with your body. There are various tactics, such as circling an opponent, cutting them off, or using a well-timed boost to get in front of their head. When a snake dies, it explodes into a burst of highly nutritious pellets, ready for consumption. Tips for Serpent Supremacy: Mastering the Arena While the gameplay is simple, becoming a truly massive snake requires a blend of patience, observation, and clever tactics. Patience is a Virtue: Don't rush into every engagement. As a small snake, your primary goal is to grow. Focus on consuming loose pellets and avoiding larger players. The Art of the Boost: Use your boost wisely. It's excellent for escaping dangerous situations or quickly grabbing a cluster of food, but over-boosting will shrink you unnecessarily. Learn to anticipate where food will be and use short bursts to get there efficiently. Circle of Life (and Death): Once you've grown to a respectable size, you can start to "circle" smaller snakes. By gradually enclosing them, you force them into a smaller and smaller space until they inevitably collide with your body. Embrace the Edge: The edges of the map can be surprisingly safe, as fewer players tend to congregate there. It’s a good place to grow in relative peace during the early stages of your game. Capitalize on Chaos: When a large snake dies, it creates a feeding frenzy. While it's tempting to dive in immediately, observe the situation. Often, other players will collide in their eagerness, leaving even more food for a patient observer. Don't Be Afraid to Die: Seriously! Each death is a learning opportunity. Pay attention to how you were eliminated and try to avoid making the same mistake twice. The beauty of Slither io is that you can restart instantly and jump back into the action. The Endless Dance: Why Slither io Remains Relevant Slither io, available to play at Slither io, is more than just a casual game; it's a testament to the power of simple yet engaging mechanics. Its low barrier to entry, combined with surprisingly deep strategic possibilities, makes it a timeless classic. Whether you're looking for a quick break, a competitive outlet, or just a chance to unwind, embracing your inner serpent in the vibrant world of Slither io is an experience well worth trying. Go forth, consume, and dominate the leaderboard!

1 month

Terrifying Escape Challenges Inside Granny Horror Survival Adventure

by reasonable.rabbit.epoq＠hidingmail.net

Introduction to Granny Horror Gameplay Granny is one of the most popular horror games in the mobile gaming world. The game creates a tense atmosphere filled with darkness, fear, and unpredictable danger. Players wake up inside an old house and must find a way to escape before time runs out. Every sound can attract danger, and every room may hide useful tools or deadly traps. https://grannyfree.io/ The simple gameplay mechanics make Granny easy to understand, but the increasing tension keeps players engaged for hours. Horror fans enjoy the thrilling experience because every match feels different. Random item locations and unpredictable enemy movement create excitement in every playthrough. The game combines stealth mechanics, puzzle-solving, and survival elements into a complete horror adventure. Players must stay quiet, move carefully, and think strategically to survive inside the terrifying house. Dark Atmosphere and Immersive Horror Experience Creepy Environment and Sound Design One of the strongest features of Granny is the frightening atmosphere. The old house contains dark hallways, broken furniture, hidden basements, and mysterious locked doors. Every area creates tension and uncertainty. The sound effects increase the horror experience dramatically. Footsteps, creaking floors, and sudden noises make every movement feel dangerous. Silence becomes just as terrifying as loud sounds because players never know where danger may appear next. The visual design also supports the horror theme. Dim lighting and shadow-filled rooms create suspense throughout the game. Even simple exploration becomes stressful because danger may appear at any moment. Fear Created Through Constant Pressure Granny creates fear through pressure instead of excessive action. Players cannot fight freely or move carelessly. One wrong decision may lead to immediate failure. This constant danger keeps players focused and emotionally involved. The limited time system adds more intensity. Players usually have only a few days to escape the house. Each failed attempt increases tension and forces players to learn from mistakes. The combination of stealth and survival mechanics creates memorable horror moments that many players continue discussing online. Survival Mechanics That Keep Players Engaged Stealth Gameplay and Smart Movement Stealth is the core mechanic of Granny. Running loudly or dropping objects may attract danger instantly. Players must crouch, hide under beds, and move slowly to avoid detection. Different areas of the house require careful observation. Some floors create noise, while certain doors open slowly and loudly. Understanding the environment becomes essential for survival. The game rewards patience and strategic thinking. Quick reactions help during emergencies, but long-term success depends on planning and observation. Puzzle Solving and Exploration Granny includes many puzzles that require exploration and logical thinking. Players must search for keys, tools, batteries, and hidden objects throughout the house. Many items have multiple purposes. A hammer may remove wooden barriers, while a key may unlock important escape routes. Players need to remember item locations and manage resources efficiently. The puzzles remain simple enough for beginners but challenging enough to maintain excitement. Exploration becomes rewarding because every discovered item may help progress toward freedom. Different Escape Routes and Replay Value Multiple Ways to Escape One reason behind the popularity of Granny is the variety of escape methods. Players can unlock doors, repair vehicles, or discover secret routes hidden inside the house. Different strategies create different experiences. Some players focus on quick escapes, while others explore every room carefully. This flexibility keeps the gameplay fresh over multiple sessions. The hidden secrets encourage replayability. Many players return to discover alternative endings and hidden features that they missed during earlier attempts. Difficulty Levels for All Players Granny includes several difficulty settings that make the game accessible for different skill levels. Beginners can choose easier modes with fewer dangers, while experienced players can select harder difficulties for more intense gameplay. Harder modes increase enemy speed, reduce available resources, and create additional challenges. These options allow players to customize the horror experience according to personal preference. This adjustable difficulty system helps Granny appeal to both casual gamers and hardcore horror fans. Why Granny Became Popular Worldwide Simple Controls and Accessible Gameplay Granny became successful partly because of its simple controls. Mobile players can easily learn movement, interaction, and hiding mechanics without complicated tutorials. The accessibility allows players from many age groups to enjoy the game. Quick learning combined with intense horror creates an experience that remains entertaining from the first session. The lightweight design also helps the game run smoothly on many devices, increasing global popularity. Viral Content and Streaming Success Many content creators helped Granny gain worldwide attention. Horror reactions, escape challenges, and gameplay videos became extremely popular on streaming platforms and social media. The unpredictable gameplay creates entertaining reactions that viewers enjoy watching. Every scream, failed escape, or close encounter becomes exciting content for audiences. Online communities continue sharing strategies, secrets, and challenge ideas related to Granny. This active fanbase helps maintain interest in the game years after release. Advanced Tips for Better Survival Learn Sound Management Techniques Sound management is extremely important in Granny. Players should avoid throwing objects unnecessarily and close doors carefully whenever possible. Listening carefully also provides valuable information. Enemy movement sounds may reveal safe paths or dangerous locations nearby. Headphones improve the overall experience because directional sound helps players understand threats more accurately. Memorize Important Locations Successful players often memorize room layouts and item spawn locations. Fast navigation becomes critical during dangerous situations. Important escape tools usually appear in random positions, but understanding the general map structure helps players search more efficiently. Practice improves confidence and reduces panic during stressful moments. Horror Elements That Make Granny Unique Psychological Fear Instead of Constant Action Unlike many action-heavy horror games, Granny focuses on psychological tension. Silence, uncertainty, and limited visibility create fear naturally. Players spend much of the game anticipating danger instead of constantly fighting enemies. This slower pacing creates stronger emotional impact. The feeling of helplessness increases immersion and makes every successful escape feel rewarding. Minimalist Design With Strong Impact Granny proves that simple design can still create powerful horror experiences. The game does not rely on advanced graphics or complex mechanics. Instead, strong atmosphere, effective sound design, and intelligent pacing create memorable gameplay. This minimalist approach allows the horror elements to remain the main focus. Many modern indie horror games use similar techniques inspired by the success of Granny. Conclusion Granny continues to attract horror fans because of intense survival gameplay, frightening atmosphere, and engaging escape mechanics. The combination of stealth, puzzles, and psychological horror creates a unique experience that remains entertaining even after multiple playthroughs. Simple controls, multiple difficulty settings, and different escape routes make the game accessible for many players around the world. Whether players enjoy exploration, suspense, or strategic survival, Granny delivers a thrilling horror adventure filled with tension and excitement. For anyone searching for a memorable horror game with challenging survival mechanics, Granny remains an excellent choice in the horror gaming genre.

1 month

[PATCH v3] dma-buf: Fix silent overflow for phys vec to sgt

by David Hu

In case MMIO size is bigger than 4G and peer2peer DMA goes through host bridge, we trigger a code path that assigns the total linked IOVA (which is greater than 4G) to mapped_len. Previously, `mapped_len` was declared as 32-bit `unsigned int`. When accumulating `size_t` lengths, this leads to a silent wrap-around. This truncation causes truncated lengths to be passed to functions like `fill_sg_entry()`. Fix this by changing `mapped_len` to `size_t` (64-bit). While at it, fix similar potential overflow issues in `calc_sg_nents` by using `size_t` for `nents` and checking against `UINT_MAX` and using `unsigned int` for the loop iterator in `fill_sg_entry` to match. Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine") Cc: stable(a)vger.kernel.org Cc: iommu(a)lists.linux.dev Reviewed-by: Pranjal Shrivastava <praan(a)google.com> Signed-off-by: David Hu <xuehaohu(a)google.com> --- Changes in v3: - Removed leftover sentence fragment from the commit message. - Kept `nents = 0` initialization (previously stated as removed in the v2 changelog) as it is strictly required for the `+=` accumulation loop in `calc_sg_nents()`. Changes in v2: - Fixed 'IVOA' -> 'IOVA' typo and expanded commit message (Claude Bot). - Added Reverse Xmas tree formatting (Pranjal). - Folded in extra bounds checking for calc_sg_nents() (Pranjal). - Folded in type consistency fix for fill_sg_entry() (Pranjal). drivers/dma-buf/dma-buf-mapping.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c index 794acff2546a..5bc769fc42ea 100644 --- a/drivers/dma-buf/dma-buf-mapping.c +++ b/drivers/dma-buf/dma-buf-mapping.c @@ -10,7 +10,7 @@ static struct scatterlist *fill_sg_entry(struct scatterlist *sgl, size_t length, dma_addr_t addr) { unsigned int len, nents; - int i; + unsigned int i; nents = DIV_ROUND_UP(length, UINT_MAX); for (i = 0; i < nents; i++) { @@ -36,7 +36,7 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, struct phys_vec *phys_vec, size_t nr_ranges, size_t size) { - unsigned int nents = 0; + size_t nents = 0; size_t i; if (!state || !dma_use_iova(state)) { @@ -51,6 +51,9 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, nents = DIV_ROUND_UP(size, UINT_MAX); } + if (nents > UINT_MAX) + return 0; + return nents; } @@ -95,9 +98,10 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach, size_t nr_ranges, size_t size, enum dma_data_direction dir) { - unsigned int nents, mapped_len = 0; struct dma_buf_dma *dma; struct scatterlist *sgl; + size_t mapped_len = 0; + unsigned int nents; dma_addr_t addr; size_t i; int ret; -- 2.54.0.794.g4f17f83d09-goog

1 month

[PATCH] dma-buf: fix UAF in dma_buf_fd() tracepoint

by David Carlier

Once FD_ADD() returns, the fd is live in the file descriptor table and a thread sharing that table can close() it before DMA_BUF_TRACE() runs. The close drops the last reference, __fput() frees the dma_buf, and the tracepoint then dereferences dmabuf to take dmabuf->name_lock -- slab-use-after-free. Split FD_ADD() back into get_unused_fd_flags() + fd_install() and emit the tracepoint between them. While the fdtable slot is reserved with a NULL file pointer, a racing close() returns -EBADF without entering __fput(), so the dma_buf stays alive across the trace. Same approach as commit 2d76319c4cbb ("dma-buf: fix UAF in dma_buf_put() tracepoint"). This undoes the FD_ADD() conversion done in commit 34dfce523c90 ("dma: convert dma_buf_fd() to FD_ADD()"); FD_ADD() has no place to hook the tracepoint safely. Reported-by: syzbot+7f4987d0afb97dd090cb(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7f4987d0afb97dd090cb Fixes: 281a22631423 ("dma-buf: add some tracepoints to debug.") Cc: stable(a)vger.kernel.org # 7.0.x Signed-off-by: David Carlier <devnexen(a)gmail.com> --- drivers/dma-buf/dma-buf.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 71f37544a5c6..d504c636dc29 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -792,9 +792,13 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags) if (!dmabuf || !dmabuf->file) return -EINVAL; - fd = FD_ADD(flags, dmabuf->file); + fd = get_unused_fd_flags(flags); + if (fd < 0) + return fd; + DMA_BUF_TRACE(trace_dma_buf_fd, dmabuf, fd); + fd_install(fd, dmabuf->file); return fd; } EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF"); -- 2.53.0

1 month

Whatsapp: +33 754.090.961, How get location in Abou Dhabi, UAE read full story .

by brekkea78＠gmail.com

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1 month

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1 month

Unleash Your Inner Blade: A Guide to the Satisfying World of Slice Master

by profound.cheetah.kect＠hidingmail.net

Ever found yourself in a moment of boredom, scrolling aimlessly, and wishing for something simple yet utterly satisfying to engage your mind? Look no further than the delightful genre of slicing games, and specifically, the incredibly addictive Slice Master. These games offer a unique blend of precision, timing, and visual gratification, making them a perfect pick-up-and-play experience for anyone looking to unwind. https://slicemasterfree.com What is Slice Master, and Why Should You Try It? At its core, Slice Master is a game about, well, slicing! Imagine a canvas filled with various shapes and objects, and your goal is to meticulously cut them into smaller, designated pieces using a virtual blade. It sounds deceptively simple, but the genius lies in its execution. The game's intuitive controls and satisfying physics make each slice feel impactful, and the challenge gradually increases, keeping you hooked. Think of it as a digital meditation, where the act of carefully dissecting objects becomes a strangely calming and rewarding experience. The visual feedback of cleanly cut shapes, often accompanied by satisfying sound effects, creates a positive loop that encourages you to keep playing. Getting Started: A Glimpse into the Gameplay Playing Slice Master is incredibly straightforward, making it accessible to gamers of all ages and skill levels. Here's a basic rundown of what you can expect: The Objective: Each level presents you with a set of objects. Your goal is to slice them into a specific number of smaller pieces, often along indicated lines or into particular shapes. The Blade: You control a virtual blade, usually by dragging your finger or mouse across the screen. The key is to make smooth, precise movements to achieve clean cuts. Precision is Key: Hitting the target lines perfectly often yields higher scores or unlocks bonus points. Messy cuts might mean restarting a section or losing points. Varying Challenges: As you progress, you'll encounter different materials that require more careful slicing, moving objects, or even time limits, adding layers of complexity to the core mechanic. Tips for Becoming a Slice Master While the game is easy to pick up, mastering it requires a bit of finesse. Here are a few friendly tips to enhance your slicing skills: Practice Makes Perfect: Don't be discouraged by imperfect cuts at first. The more you play, the better your hand-eye coordination and precision will become. Observe the Target: Before you make your first cut, take a moment to analyze the object and the desired outcome. Visualize your cut path. Smooth and Steady Wins the Race: Avoid jerky movements. A slow, deliberate drag of your blade is often more effective than a quick, frantic swipe. Utilize the Edges: Sometimes, using the edges of the object as a guide for your cuts can help you achieve straighter and more accurate slices. Don't Be Afraid to Restart: If a cut goes horribly wrong, many levels allow you to restart that particular segment. It's better to restart and achieve a perfect score than to muddle through with a subpar cut. Conclusion: A Simple Joy Slice Master and similar slicing games offer a delightful escape from the hustle and bustle of everyday life. Their uncomplicated yet engaging gameplay provides a sense of accomplishment and a unique form of digital satisfaction. Whether you have five minutes to spare or an hour to unwind, diving into the world of precise cuts and satisfying visuals is a worthwhile endeavor. So, grab your virtual blade and prepare to experience the quiet joy of becoming a true Slice Master!

1 month

[PATCH v2] dma-buf: set SB_I_NOEXEC and SB_I_NODEV on the pseudo filesystem

by John Hubbard

The dma-buf pseudo filesystem dispenses S_ANON_INODE inodes via alloc_anon_inode() but never sets SB_I_NOEXEC on its superblock. Since commit 1e7ab6f67824 ("anon_inode: rework assertions") in 6.17, path_noexec() warns on exactly that combination, so an mmap() on any dma-buf fd trips the warning: WARNING: CPU: 11 PID: 121813 at fs/exec.c:118 path_noexec+0x47/0x50 do_mmap+0x2b5/0x680 vm_mmap_pgoff+0x129/0x210 ksys_mmap_pgoff+0x177/0x240 __x64_sys_mmap+0x33/0x70 dma-bufs have no business being executable, which is the invariant that the new assertion is enforcing. Set SB_I_NOEXEC. Also set SB_I_NODEV, since the pseudo filesystem creates no device nodes. Reproducer on a CONFIG_DEBUG_VFS=y kernel: make -C tools/testing/selftests/dmabuf-heaps sudo ./tools/testing/selftests/dmabuf-heaps/dmabuf-heap -t system The selftest allocates from /dev/dma_heap/system and mmaps the returned fd, which trips the warning without this patch. Fixes: 1e7ab6f67824 ("anon_inode: rework assertions") Cc: stable(a)vger.kernel.org Reviewed-by: Christian Brauner (Amutable) <brauner(a)kernel.org> Signed-off-by: John Hubbard <jhubbard(a)nvidia.com> --- Changes since v1: * Also set SB_I_NODEV (suggested by Christian Brauner). * Added Christian Brauner's Reviewed-by tag (thanks!) drivers/dma-buf/dma-buf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 71f37544a5c6..ea1ddd4293b2 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -216,6 +216,8 @@ static int dma_buf_fs_init_context(struct fs_context *fc) if (!ctx) return -ENOMEM; ctx->dops = &dma_buf_dentry_ops; + fc->s_iflags |= SB_I_NOEXEC; + fc->s_iflags |= SB_I_NODEV; return 0; } base-commit: 6779b50faa562e6cca1aa6a4649a4d764c6c7e28 -- 2.54.0

1 month

[PATCH v2] dma-buf: Fix silent overflow for phys vec to sgt

by David Hu

In case MMIO size is bigger than 4G and peer2peer DMA goes through host bridge, we trigger a code path that assigns the total linked IOVA (which is greater than 4G) to mapped_len. Previously, `mapped_len` was declared as 32-bit `unsigned int`. When accumulating `size_t` lengths, this leads to a silent wrap-around. This truncation causes truncated lengths to be passed to functions like `fill_sg_entry()`. Fix this by changing `mapped_len` to `size_t` (64-bit). While at it, fix similar potential overflow issues in `calc_sg_nents` by using `size_t` for `nents` and checking against `UINT_MAX` and using `unsigned int` for the loop iterator in `fill_sg_entry` to match. to mapped_len, and leading to a silent overflow Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine") Cc: stable(a)vger.kernel.org Cc: iommu(a)lists.linux.dev Reviewed-by: Pranjal Shrivastava <praan(a)google.com> Signed-off-by: David Hu <xuehaohu(a)google.com> --- Changes in v2: Fixed 'IVOA' -> 'IOVA' typo and expanded commit message (Claude Bot). Added Reverse Xmas tree formatting (Pranjal). Folded in extra bounds checking for calc_sg_nents() (Pranjal). Folded in type consistency fix for fill_sg_entry() (Pranjal). Droped unnecessary `nents = 0` initialization (Claude Bot). drivers/dma-buf/dma-buf-mapping.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c index 794acff2546a..5bc769fc42ea 100644 --- a/drivers/dma-buf/dma-buf-mapping.c +++ b/drivers/dma-buf/dma-buf-mapping.c @@ -10,7 +10,7 @@ static struct scatterlist *fill_sg_entry(struct scatterlist *sgl, size_t length, dma_addr_t addr) { unsigned int len, nents; - int i; + unsigned int i; nents = DIV_ROUND_UP(length, UINT_MAX); for (i = 0; i < nents; i++) { @@ -36,7 +36,7 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, struct phys_vec *phys_vec, size_t nr_ranges, size_t size) { - unsigned int nents = 0; + size_t nents = 0; size_t i; if (!state || !dma_use_iova(state)) { @@ -51,6 +51,9 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, nents = DIV_ROUND_UP(size, UINT_MAX); } + if (nents > UINT_MAX) + return 0; + return nents; } @@ -95,9 +98,10 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach, size_t nr_ranges, size_t size, enum dma_data_direction dir) { - unsigned int nents, mapped_len = 0; struct dma_buf_dma *dma; struct scatterlist *sgl; + size_t mapped_len = 0; + unsigned int nents; dma_addr_t addr; size_t i; int ret; -- 2.54.0.794.g4f17f83d09-goog

1 month

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