The exec ioctl allows userspace to specify an arbitrary num_syncs value. Without bounds checking, a very large num_syncs can force an excessively large allocation, leading to kernel warnings from the page allocator as below.
Introduce XE_EXEC_MAX_SYNCS (set to 64) and reject any request exceeding this limit.
" ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1217 at mm/page_alloc.c:5124 __alloc_frozen_pages_noprof+0x2f8/0x2180 mm/page_alloc.c:5124 ... Call Trace: <TASK> alloc_pages_mpol+0xe4/0x330 mm/mempolicy.c:2416 ___kmalloc_large_node+0xd8/0x110 mm/slub.c:4317 __kmalloc_large_node_noprof+0x18/0xe0 mm/slub.c:4348 __do_kmalloc_node mm/slub.c:4364 [inline] __kmalloc_noprof+0x3d4/0x4b0 mm/slub.c:4388 kmalloc_noprof include/linux/slab.h:909 [inline] kmalloc_array_noprof include/linux/slab.h:948 [inline] xe_exec_ioctl+0xa47/0x1e70 drivers/gpu/drm/xe/xe_exec.c:158 drm_ioctl_kernel+0x1f1/0x3e0 drivers/gpu/drm/drm_ioctl.c:797 drm_ioctl+0x5e7/0xc50 drivers/gpu/drm/drm_ioctl.c:894 xe_drm_ioctl+0x10b/0x170 drivers/gpu/drm/xe/xe_device.c:224 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xbb/0x380 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f ... "
v2: Add "Reported-by" and Cc stable kernels.
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6450 Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Reported-by: Koen Koning koen.koning@intel.com Reported-by: Peter Senna Tschudin peter.senna@linux.intel.com Cc: stable@vger.kernel.org Cc: Matthew Brost matthew.brost@intel.com Signed-off-by: Shuicheng Lin shuicheng.lin@intel.com --- drivers/gpu/drm/xe/xe_exec.c | 5 +++++ include/uapi/drm/xe_drm.h | 1 + 2 files changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/xe/xe_exec.c b/drivers/gpu/drm/xe/xe_exec.c index 4d81210e41f5..01c56fd95d5b 100644 --- a/drivers/gpu/drm/xe/xe_exec.c +++ b/drivers/gpu/drm/xe/xe_exec.c @@ -162,6 +162,11 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file) }
if (args->num_syncs) { + if (XE_IOCTL_DBG(xe, args->num_syncs > XE_EXEC_MAX_SYNCS)) { + err = -EINVAL; + goto err_exec_queue; + } + syncs = kcalloc(args->num_syncs, sizeof(*syncs), GFP_KERNEL); if (!syncs) { err = -ENOMEM; diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h index 47853659a705..1901ca26621a 100644 --- a/include/uapi/drm/xe_drm.h +++ b/include/uapi/drm/xe_drm.h @@ -1463,6 +1463,7 @@ struct drm_xe_exec { /** @exec_queue_id: Exec queue ID for the batch buffer */ __u32 exec_queue_id;
+#define XE_EXEC_MAX_SYNCS 64 /** @num_syncs: Amount of struct drm_xe_sync in array. */ __u32 num_syncs;