From: Harry Wentland <harry.wentland@amd.com> stable inclusion from stable-v6.6.143 commit 7fc4fab4acc307ad2903312c195872b2953d32c3 category: bugfix bugzilla: 15829 CVE: CVE-2026-53135 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit adf67034b1f61f7119295208085bfd43f85f56af upstream. [Why & How] dp_sdp_message_debugfs_write() dereferences connector->base.state->crtc without checking for NULL. A connector can be connected but not bound to any CRTC (e.g. after hot-plug before the next atomic commit), causing a kernel crash when writing to the sdp_message debugfs node. The function also ignores the user-provided size argument and always passes 36 bytes to copy_from_user(), reading past the user buffer when size < 36. Fix both issues by: - Returning -ENODEV when connector->base.state or state->crtc is NULL - Clamping write_size to min(size, sizeof(data)) Fixes: c7ba3653e977 ("drm/amd/display: Generic SDP message access in amdgpu") Assisted-by: Copilot:claude-opus-4.6 Reviewed-by: Alex Hung <alex.hung@amd.com> Signed-off-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Ray Wu <ray.wu@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> (cherry picked from commit 6ab4c36a522842ff70474a1c0af2e40e50fc8300) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zhang Hongtao <zhanghongtao35@huawei.com> --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c index c8609595f324b..4b8101bf62e9d 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c @@ -1230,8 +1230,13 @@ static ssize_t dp_sdp_message_debugfs_write(struct file *f, const char __user *b if (size == 0) return 0; + if (!connector->base.state || !connector->base.state->crtc) + return -ENODEV; + acrtc_state = to_dm_crtc_state(connector->base.state->crtc->state); + write_size = min_t(size_t, size, sizeof(data)); + r = copy_from_user(data, buf, write_size); write_size -= r; -- 2.43.0