From: Michael Bommarito Date: Sun, 17 May 2026 13:17:42 +0000 (-0400) Subject: drm/amdgpu: fix lock leak on ENOMEM in AMDGPU_GEM_OP_GET_MAPPING_INFO X-Git-Tag: v7.1-rc6~13^2~2^2~18 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=2e7f55eb408c3f72ee1957a0d0ad11d8648a6379;p=thirdparty%2Fkernel%2Flinux.git drm/amdgpu: fix lock leak on ENOMEM in AMDGPU_GEM_OP_GET_MAPPING_INFO The AMDGPU_GEM_OP_GET_MAPPING_INFO branch of amdgpu_gem_op_ioctl() holds three cleanup-tracked resources before calling kvcalloc(): the drm_gem_object reference from drm_gem_object_lookup(), the drm_exec lock on the looked-up GEM via drm_exec_lock_obj(), and the drm_exec lock on the per-process VM root page directory via amdgpu_vm_lock_pd(). All three are released by the out_exec label that every other error path in this function jumps to. The kvcalloc() failure path returns -ENOMEM directly, skipping out_exec and leaking all three. The leaked per-process VM root PD dma_resv lock is the load-bearing leak: any subsequent operation on the same VM (further GEM ops, command-submission, eviction, TTM shrinker callbacks) blocks on the held lock. DRM_IOCTL_AMDGPU_GEM_OP is DRM_AUTH | DRM_RENDER_ALLOW, so this is an unprivileged-local denial of service against the caller's GPU context, reachable by any process with /dev/dri/renderD* access. Route the failure through out_exec so drm_exec_fini() and drm_gem_object_put() run. Reproduced on stock 7.0.0-10, Ryzen 7 5700U / Radeon Vega (Lucienne): the failing ioctl returns -ENOMEM and a second GET_MAPPING_INFO on the same fd then blocks in drm_exec_lock_obj() on the leaked dma_resv. SIGKILL on the caller does not reap the task; the fd-release path during process exit goes through amdgpu_gem_object_close() -> drm_exec_prepare_obj() on the same lock, leaving the task in D state until the box is rebooted. The patched kernel was not rebuilt and re-tested on this hardware; the fix is mechanical. Tested on a single Lucienne / Vega box only. Ziyi Guo posted an independent INT_MAX-bound check for args->num_entries in the same branch [1]; the two patches are complementary and can land in either order. Fixes: 4d82724f7f2b ("drm/amdgpu: Add mapping info option for GEM_OP ioctl") Link: https://lore.kernel.org/all/20260208000255.4073363-1-n7l8m4@u.northwestern.edu/ # [1] Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Alex Deucher (cherry picked from commit b69d3256d79de15f54c322986ff4da68f1d65b0a) Cc: stable@vger.kernel.org --- diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c index 123d4a09114df..06dd2e8a5b471 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -1094,8 +1094,10 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data, * be retried. */ vm_entries = kvcalloc(args->num_entries, sizeof(*vm_entries), GFP_KERNEL); - if (!vm_entries) - return -ENOMEM; + if (!vm_entries) { + r = -ENOMEM; + goto out_exec; + } amdgpu_vm_bo_va_for_each_valid_mapping(bo_va, mapping) { if (num_mappings < args->num_entries) {