{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38449","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T04:51:24.018Z","datePublished":"2025-07-25T15:27:30.702Z","dateUpdated":"2026-08-05T12:01:59.291Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:01:59.291Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/gem: Acquire references on GEM handles for framebuffers\n\nA GEM handle can be released while the GEM buffer object is attached\nto a DRM framebuffer. This leads to the release of the dma-buf backing\nthe buffer object, if any. [1] Trying to use the framebuffer in further\nmode-setting operations leads to a segmentation fault. Most easily\nhappens with driver that use shadow planes for vmap-ing the dma-buf\nduring a page flip. An example is shown below.\n\n[  156.791968] ------------[ cut here ]------------\n[  156.796830] WARNING: CPU: 2 PID: 2255 at drivers/dma-buf/dma-buf.c:1527 dma_buf_vmap+0x224/0x430\n[...]\n[  156.942028] RIP: 0010:dma_buf_vmap+0x224/0x430\n[  157.043420] Call Trace:\n[  157.045898]  <TASK>\n[  157.048030]  ? show_trace_log_lvl+0x1af/0x2c0\n[  157.052436]  ? show_trace_log_lvl+0x1af/0x2c0\n[  157.056836]  ? show_trace_log_lvl+0x1af/0x2c0\n[  157.061253]  ? drm_gem_shmem_vmap+0x74/0x710\n[  157.065567]  ? dma_buf_vmap+0x224/0x430\n[  157.069446]  ? __warn.cold+0x58/0xe4\n[  157.073061]  ? dma_buf_vmap+0x224/0x430\n[  157.077111]  ? report_bug+0x1dd/0x390\n[  157.080842]  ? handle_bug+0x5e/0xa0\n[  157.084389]  ? exc_invalid_op+0x14/0x50\n[  157.088291]  ? asm_exc_invalid_op+0x16/0x20\n[  157.092548]  ? dma_buf_vmap+0x224/0x430\n[  157.096663]  ? dma_resv_get_singleton+0x6d/0x230\n[  157.101341]  ? __pfx_dma_buf_vmap+0x10/0x10\n[  157.105588]  ? __pfx_dma_resv_get_singleton+0x10/0x10\n[  157.110697]  drm_gem_shmem_vmap+0x74/0x710\n[  157.114866]  drm_gem_vmap+0xa9/0x1b0\n[  157.118763]  drm_gem_vmap_unlocked+0x46/0xa0\n[  157.123086]  drm_gem_fb_vmap+0xab/0x300\n[  157.126979]  drm_atomic_helper_prepare_planes.part.0+0x487/0xb10\n[  157.133032]  ? lockdep_init_map_type+0x19d/0x880\n[  157.137701]  drm_atomic_helper_commit+0x13d/0x2e0\n[  157.142671]  ? drm_atomic_nonblocking_commit+0xa0/0x180\n[  157.147988]  drm_mode_atomic_ioctl+0x766/0xe40\n[...]\n[  157.346424] ---[ end trace 0000000000000000 ]---\n\nAcquiring GEM handles for the framebuffer's GEM buffer objects prevents\nthis from happening. The framebuffer's cleanup later puts the handle\nreferences.\n\nCommit 1a148af06000 (\"drm/gem-shmem: Use dma_buf from GEM object\ninstance\") triggers the segmentation fault easily by using the dma-buf\nfield more widely. The underlying issue with reference counting has\nbeen present before.\n\nv2:\n- acquire the handle instead of the BO (Christian)\n- fix comment style (Christian)\n- drop the Fixes tag (Christian)\n- rename err_ gotos\n- add missing Link tag"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is triggered purely through DRM ioctls (PRIME_FD_TO_HANDLE, ADDFB2, GEM_CLOSE, MODE_ATOMIC/PAGE_FLIP) on a local device node /dev/dri/card*. There is no network or remote-peer data path into drm_gem_fb_init_with_funcs() or drm_gem_object_handle_put_unlocked().\nAC:L - The attacker performs the entire sequence themselves — import a dma-buf, create a framebuffer, close the GEM handle, then commit the framebuffer — and the resulting release of the still-referenced dma-buf is deterministic, with no race or memory-layout condition outside the attacker's control. Where a window is involved (begin_fb_access in prepare_planes vs. end_fb_access in cleanup_planes), the attacker drives both sides from their own threads.\nPR:L - Only an unprivileged local account with access to a DRM primary node is needed (video group, active-seat ACL, Android graphics group); ADDFB2/RMFB/GEM_CLOSE require no master or auth flags at all. DRM master, needed for the atomic commit, is handed out by drm_master_open() to the first opener of the node with no capability check, and is also available via DRM leases — no real root is required.\nUI:N - A single attacker-controlled process performs every step — buffer import, framebuffer creation, handle close, and the mode-setting commit. No victim action or cooperating process is involved.\nS:U - The premature release and subsequent misuse of the GEM object's dma-buf occur entirely within the kernel's own security authority on the same host. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a reference-counting/lifetime defect that releases the dma-buf backing a framebuffer that remains live and in active use by plane state, the scanout engine and shadow-plane kernel mappings — a use-after-free-class flaw. Such premature release of a GEM/dma-buf backing store, with attacker-controlled heap grooming via DUMB_CREATE and repeated import/close cycles, is leverageable into disclosure of reallocated kernel memory contents.\nI:H - The same missing handle reference lets the kernel continue writing through stale framebuffer state (shadow-plane blits, damage handling) into storage whose backing reference has been dropped, and the unguarded dma_buf_end_cpu_access() path performs an indirect call through dmabuf->ops on a released/invalid dma_buf. This gives a memory-corruption and control-flow primitive rather than a benign failure.\nA:H - The documented result is a WARNING splat in dma_buf_vmap() (a panic on the widely deployed panic_on_warn configurations) and a kernel oops — dma_buf_end_cpu_access() only does WARN_ON(!dmabuf) without returning and then dereferences dmabuf->resv and dmabuf->ops. Any local user with DRM access can trigger this repeatedly to crash the machine."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_gem.c","drivers/gpu/drm/drm_gem_framebuffer_helper.c","drivers/gpu/drm/drm_internal.h"],"versions":[{"version":"319c933c71f3dbdb2b3274d1634d3494c70efa06","lessThan":"cb4c956a15f8b7f870649454771fc3761f504b5f","status":"affected","versionType":"git"},{"version":"319c933c71f3dbdb2b3274d1634d3494c70efa06","lessThan":"08480e285c6a82ce689008d643e4a51db0aaef8b","status":"affected","versionType":"git"},{"version":"319c933c71f3dbdb2b3274d1634d3494c70efa06","lessThan":"3cf520d9860d4ec9f7f32068825da31f18dd3f25","status":"affected","versionType":"git"},{"version":"319c933c71f3dbdb2b3274d1634d3494c70efa06","lessThan":"5307dce878d4126e1b375587318955bd019c3741","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_gem.c","drivers/gpu/drm/drm_gem_framebuffer_helper.c","drivers/gpu/drm/drm_internal.h"],"versions":[{"version":"3.12","status":"affected"},{"version":"0","lessThan":"3.12","status":"unaffected","versionType":"semver"},{"version":"6.6.99","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.39","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.15.7","lessThanOrEqual":"6.15.*","status":"unaffected","versionType":"semver"},{"version":"6.16","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12","versionEndExcluding":"6.6.99"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12","versionEndExcluding":"6.12.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12","versionEndExcluding":"6.15.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12","versionEndExcluding":"6.16"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/cb4c956a15f8b7f870649454771fc3761f504b5f"},{"url":"https://git.kernel.org/stable/c/08480e285c6a82ce689008d643e4a51db0aaef8b"},{"url":"https://git.kernel.org/stable/c/3cf520d9860d4ec9f7f32068825da31f18dd3f25"},{"url":"https://git.kernel.org/stable/c/5307dce878d4126e1b375587318955bd019c3741"}],"title":"drm/gem: Acquire references on GEM handles for framebuffers","x_generator":{"engine":"bippy-1.2.0"}}}}