Linaro-mm-sig

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[PATCH] drm/prime: Fix unsupervised rb_tree corruption in drm_prime_remove_buf_handle

by w15303746062＠163.com

From: Mingyu Wang <25181214217(a)stu.xidian.edu.cn> Syzkaller fuzzer triggered a kernel panic via a WARNING in drm_prime_destroy_file_private() due to a non-empty prime rb_tree. The root cause is a complete lack of synchronization in the teardown path. While the import path (drm_gem_prime_fd_to_handle) holds the &file_priv->prime.lock during lookup and insertion, the deletion path (drm_prime_remove_buf_handle) traverses and mutates both the 'handles' and 'dmabufs' rb_trees without acquiring any mutex. When multiple threads concurrently close GEM handles or interleave import and close operations, the pointers and balance states of the rb_tree nodes get corrupted. As a result, certain members are erased from one tree but remain orphaned in the other. Upon process exit, the final sanity check triggers the WARNING. [ 448.919314][T19739] ------------[ cut here ]------------ [ 448.945387][T19739] WARNING: CPU: 0 PID: 19739 at drivers/gpu/drm/drm_prime.c:223 drm_prime_destroy_file_private+0x43/0x60 ... [ 449.056535][T19739] Call Trace: [ 449.056544][T19739] <TASK> [ 449.056553][T19739] drm_file_free.part.0+0x805/0xcf0 [ 449.056652][T19739] drm_close_helper.isra.0+0x183/0x1f0 [ 449.056677][T19739] drm_release+0x1ab/0x360 [ 449.056719][T19739] __fput+0x402/0xb50 [ 449.056783][T19739] task_work_run+0x16b/0x260 [ 449.056883][T19739] exit_to_user_mode_loop+0xf9/0x130 [ 449.056931][T19739] do_syscall_64+0x424/0xfa0 [ 449.056977][T19739] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 449.057268][T19739] </TASK> [ 449.057295][T19739] Kernel panic - not syncing: kernel: panic_on_warn set ... Fix this by acquiring the prime_fpriv->lock mutex around the rb_tree lookup and erasure logic. To respect the locking rules and avoid potential deadlocks with driver-specific memory cleanups, assign the target node to a temporary pointer and defer the dma_buf_put() and kfree() operations until after the mutex is safely dropped. Fixes: ea2aa97ca37a ("drm/gem: Fix GEM handle release errors") Cc: stable(a)vger.kernel.org Signed-off-by: Mingyu Wang <25181214217(a)stu.xidian.edu.cn> --- drivers/gpu/drm/drm_prime.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 9b44c78cd77f..26319c638e0f 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -190,6 +190,9 @@ void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, uint32_t handle) { struct rb_node *rb; + struct drm_prime_member *found = NULL; + + mutex_lock(&prime_fpriv->lock); rb = prime_fpriv->handles.rb_node; while (rb) { @@ -200,8 +203,7 @@ void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, rb_erase(&member->handle_rb, &prime_fpriv->handles); rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs); - dma_buf_put(member->dma_buf); - kfree(member); + found = member; break; } else if (member->handle < handle) { rb = rb->rb_right; @@ -209,6 +211,13 @@ void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, rb = rb->rb_left; } } + mutex_unlock(&prime_fpriv->lock); + + /* Defer resource release outside the mutex to prevent deadlocks */ + if (found) { + dma_buf_put(found->dma_buf); + kfree(found); + } } void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv) -- 2.34.1

4 months, 1 week

[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

4 months, 1 week

[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

4 months, 1 week

[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

4 months, 1 week

[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

4 months, 1 week

[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

4 months, 1 week

[PATCH] 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 the code path to assign total linked IVOA, greater than 4G to mapped_len, and leading to a silent overflow Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine") Signed-off-by: David Hu <xuehaohu(a)google.com> --- drivers/dma-buf/dma-buf-mapping.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c index 794acff2546a..658064140357 100644 --- a/drivers/dma-buf/dma-buf-mapping.c +++ b/drivers/dma-buf/dma-buf-mapping.c @@ -95,7 +95,8 @@ 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; + unsigned int nents = 0; + size_t mapped_len = 0; struct dma_buf_dma *dma; struct scatterlist *sgl; dma_addr_t addr; -- 2.54.0.563.g4f69b47b94-goog

4 months, 1 week

[PATCH v14 0/6] rust: drm: gem: shmem: Add sg_table() function

by Lyude Paul

(was previously Rust bindings for gem shmem) Most of this patch series has already been pushed upstream, this is just the second half of the patch series that has not been pushed yet + some additional changes which were required to implement changes requested by the mailing list. This patch series is originally from Asahi, previously posted by Daniel Almeida. The previous version of the patch series can be found here: https://patchwork.freedesktop.org/series/164580/ Branch with patches applied available here: https://gitlab.freedesktop.org/lyudess/linux/-/commits/rust/gem-shmem This patch series applies on top of drm-rust-next with the following dependencies applied: https://lkml.org/lkml/2026/5/26/1960 Lyude Paul (6): rust: faux: Allow retrieving a bound Device rust: gem: shmem: Fix Default implementation for ObjectConfig rust: drm: gem: s/device::Device/Device/ for shmem.rs drm/gem/shmem: Introduce __drm_gem_shmem_free_sgt_locked() rust: drm: gem/shmem: Add DmaResvGuard helper rust: drm: gem: Introduce shmem::Object::sg_table() drivers/gpu/drm/drm_gem_shmem_helper.c | 32 ++- include/drm/drm_gem_shmem_helper.h | 1 + rust/kernel/drm/gem/shmem.rs | 264 +++++++++++++++++++++++-- rust/kernel/faux.rs | 7 +- 4 files changed, 279 insertions(+), 25 deletions(-) base-commit: 2cf1840b0fa7637b6731fd554529f8d57ea34c04 prerequisite-patch-id: c8ade07eec6e9c9e875800b114137c459d362e4e prerequisite-patch-id: dc4f750bc885b867842587b994261f43602bc6a8 -- 2.54.0

4 months, 1 week

[PATCH] dma-buf: Move dma_resv_assert_held() after input validation

by lirongqing

From: Li RongQing <lirongqing(a)baidu.com> Move dma_resv_assert_held() after the validation of 'attach' and 'attach->dmabuf' to avoid a potential null pointer dereference if the function is ever called with invalid arguments. Signed-off-by: Li RongQing <lirongqing(a)baidu.com> --- drivers/dma-buf/dma-buf-mapping.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c index 794acff..e6ecd6c 100644 --- a/drivers/dma-buf/dma-buf-mapping.c +++ b/drivers/dma-buf/dma-buf-mapping.c @@ -102,12 +102,12 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach, size_t i; int ret; - dma_resv_assert_held(attach->dmabuf->resv); - if (WARN_ON(!attach || !attach->dmabuf || !provider)) /* This function is supposed to work on MMIO memory only */ return ERR_PTR(-EINVAL); + dma_resv_assert_held(attach->dmabuf->resv); + dma = kzalloc_obj(*dma); if (!dma) return ERR_PTR(-ENOMEM); -- 2.9.4

4 months, 1 week

Re: DEPT (the dependency tracker) as AI review prompt?

by Yunseong Kim

Hi Harry, On 5/23/26 16:34, Harry Yoo wrote: > > > On 5/23/26 11:00 PM, Yunseong Kim wrote: >> I've previously experimented with running DEPT alongside syzkaller fuzzing, >> and many hung tasks missed by lockdep are caught by DEPT, but the resulting >> high volume of reports makes it easy for issues to get lost in the massive >> log output. Sorting through that output manually is a huge bottleneck, so >> leveraging a well-crafted AI prompt to triage the warnings and filter out >> the false positives would be incredibly valuable. > > I mean both 1) detection of deadlock issues AND 2) false positive elimination with AI. I completely agree. Implanting DEPT's model into an AI review prompt is a great idea. As you suggested, the patterns we develop for the AI could provide valuable feedback to enhance DEPT's itself. > If the review prompt is only used to eliminate DEPT's false positives, I think that would be quite hard to get broad use. > > Someone would have to build out-of-tree DEPT, collect the reports, and then feed those back into the AI. I don't think building that kind of pipeline would actually work well in practice. I also have a huge dept report of DEPT reports, and manually reviewing all of them is makes me sigh. The constant kernel rebuilds required for lockup testing every time are also quite expensive. Thanks for the summary! Best Regards, Yunseong

4 months, 2 weeks

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