[lts92] Address CVE-2025-38449 #637
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jira VULN-136707 cve-pre CVE-2025-38449 commit-author ChunyouTang <tangchunyou@163.com> commit 7df34a6 when goto err_free, the object had init, so it should be release when fail. Signed-off-by: ChunyouTang <tangchunyou@163.com> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Link: https://patchwork.freedesktop.org/patch/msgid/20221119064131.364-1-tangchunyou@163.com (cherry picked from commit 7df34a6) Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com>
jira VULN-136707 cve CVE-2025-38449 commit-author Thomas Zimmermann <tzimmermann@suse.de> commit 5307dce upstream-diff Use mutex_lock/mutex_unlock in drm_gem_object_handle_get_unlocked instead of guard(mutex), which is not available in this kernel A GEM handle can be released while the GEM buffer object is attached to a DRM framebuffer. This leads to the release of the dma-buf backing the buffer object, if any. [1] Trying to use the framebuffer in further mode-setting operations leads to a segmentation fault. Most easily happens with driver that use shadow planes for vmap-ing the dma-buf during a page flip. An example is shown below. [ 156.791968] ------------[ cut here ]------------ [ 156.796830] WARNING: CPU: 2 PID: 2255 at drivers/dma-buf/dma-buf.c:1527 dma_buf_vmap+0x224/0x430 [...] [ 156.942028] RIP: 0010:dma_buf_vmap+0x224/0x430 [ 157.043420] Call Trace: [ 157.045898] <TASK> [ 157.048030] ? show_trace_log_lvl+0x1af/0x2c0 [ 157.052436] ? show_trace_log_lvl+0x1af/0x2c0 [ 157.056836] ? show_trace_log_lvl+0x1af/0x2c0 [ 157.061253] ? drm_gem_shmem_vmap+0x74/0x710 [ 157.065567] ? dma_buf_vmap+0x224/0x430 [ 157.069446] ? __warn.cold+0x58/0xe4 [ 157.073061] ? dma_buf_vmap+0x224/0x430 [ 157.077111] ? report_bug+0x1dd/0x390 [ 157.080842] ? handle_bug+0x5e/0xa0 [ 157.084389] ? exc_invalid_op+0x14/0x50 [ 157.088291] ? asm_exc_invalid_op+0x16/0x20 [ 157.092548] ? dma_buf_vmap+0x224/0x430 [ 157.096663] ? dma_resv_get_singleton+0x6d/0x230 [ 157.101341] ? __pfx_dma_buf_vmap+0x10/0x10 [ 157.105588] ? __pfx_dma_resv_get_singleton+0x10/0x10 [ 157.110697] drm_gem_shmem_vmap+0x74/0x710 [ 157.114866] drm_gem_vmap+0xa9/0x1b0 [ 157.118763] drm_gem_vmap_unlocked+0x46/0xa0 [ 157.123086] drm_gem_fb_vmap+0xab/0x300 [ 157.126979] drm_atomic_helper_prepare_planes.part.0+0x487/0xb10 [ 157.133032] ? lockdep_init_map_type+0x19d/0x880 [ 157.137701] drm_atomic_helper_commit+0x13d/0x2e0 [ 157.142671] ? drm_atomic_nonblocking_commit+0xa0/0x180 [ 157.147988] drm_mode_atomic_ioctl+0x766/0xe40 [...] [ 157.346424] ---[ end trace 0000000000000000 ]--- Acquiring GEM handles for the framebuffer's GEM buffer objects prevents this from happening. The framebuffer's cleanup later puts the handle references. Commit 1a148af ("drm/gem-shmem: Use dma_buf from GEM object instance") triggers the segmentation fault easily by using the dma-buf field more widely. The underlying issue with reference counting has been present before. v2: - acquire the handle instead of the BO (Christian) - fix comment style (Christian) - drop the Fixes tag (Christian) - rename err_ gotos - add missing Link tag Suggested-by: Christian König <christian.koenig@amd.com> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Link: https://elixir.bootlin.com/linux/v6.15/source/drivers/gpu/drm/drm_gem.c#L241 # [1] Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Anusha Srivatsa <asrivats@redhat.com> Cc: Christian König <christian.koenig@amd.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: <stable@vger.kernel.org> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://lore.kernel.org/r/20250630084001.293053-1-tzimmermann@suse.de (cherry picked from commit 5307dce) Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com> squsah with acquire
kerneltoast
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Oct 21, 2025
jira VULN-136707 cve-bf CVE-2025-38449 commit-author Thomas Zimmermann <tzimmermann@suse.de> commit f6bfc9a upstream-diff Minor conflict in drm_framebuffer.h due to different fields being present in struct drm_framebuffer. Also, add mutex_unlock in the new return path in drm_gem_object_handle_get_if_exists_unlocked since this version of the kernel is not using guard(mutex) Acquire GEM handles in drm_framebuffer_init() and release them in the corresponding drm_framebuffer_cleanup(). Ties the handle's lifetime to the framebuffer. Not all GEM buffer objects have GEM handles. If not set, no refcounting takes place. This is the case for some fbdev emulation. This is not a problem as these GEM objects do not use dma-bufs and drivers will not release them while fbdev emulation is running. Framebuffer flags keep a bit per color plane of which the framebuffer holds a GEM handle reference. As all drivers use drm_framebuffer_init(), they will now all hold dma-buf references as fixed in commit 5307dce ("drm/gem: Acquire references on GEM handles for framebuffers"). In the GEM framebuffer helpers, restore the original ref counting on buffer objects. As the helpers for handle refcounting are now no longer called from outside the DRM core, unexport the symbols. v3: - don't mix internal flags with mode flags (Christian) v2: - track framebuffer handle refs by flag - drop gma500 cleanup (Christian) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Fixes: 5307dce ("drm/gem: Acquire references on GEM handles for framebuffers") Reported-by: Bert Karwatzki <spasswolf@web.de> Closes: https://lore.kernel.org/dri-devel/20250703115915.3096-1-spasswolf@web.de/ Tested-by: Bert Karwatzki <spasswolf@web.de> Tested-by: Mario Limonciello <superm1@kernel.org> Tested-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Anusha Srivatsa <asrivats@redhat.com> Cc: Christian König <christian.koenig@amd.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: <stable@vger.kernel.org> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://lore.kernel.org/r/20250707131224.249496-1-tzimmermann@suse.de (cherry picked from commit f6bfc9a) Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com>
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Added braces! Moved internal_flags. Thanks reviewers! |
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Background
The original intent was to backport
9c53de76fa599 drm/gem: Acquire references on GEM handles for framebuffersto address CVE-2025-38449. This ended up requiring one prerequisite (7df34a6) and had one upstream bugfix (f6bfc9a). There are some differences from the upstream mostly because the original change uses guard(mutex) which this kernel does not have. The change to mutex_lock/mutex_unlock is straightforward though and noted in the upstream-diff sections.Commits
Build Log
Testing
selftest-5.14.0-284.30.1.el9_2.92ciq_lts.12.1.x86_64-1.log
selftest-5.14.0-bmastbergen_ciqlts9_2_vuln-136707-60eb1cf93533+-1.log