From: Ashutosh Desai <ashutoshdesai993@gmail.com> stable inclusion from stable-v6.6.140 commit 6b992591e04f2cce813bcf239b354f375bbf84d3 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15462 CVE: CVE-2026-46209 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 3d4c2268bd7243c3780fe32bf24ff876da272acf upstream. drm_gem_fb_init_with_funcs() computes sub-sampled plane dimensions using plain integer division: unsigned int width = mode_cmd->width / (i ? info->hsub : 1); unsigned int height = mode_cmd->height / (i ? info->vsub : 1); However, the ioctl-level framebuffer_check() in drm_framebuffer.c uses drm_format_info_plane_width/height() which round up dimensions via DIV_ROUND_UP(). This inconsistency corrupts the subsequent GEM object size check for certain pixel format and dimension combinations. For example, with NV12 (vsub=2) and a 1-pixel-tall framebuffer the GEM size validation path sees height=0 instead of height=1. The expression (height - 1) then wraps to UINT_MAX as an unsigned int, causing min_size to overflow and wrap back to a small value. A tiny GEM object therefore passes the size guard, yet when the GPU accesses the chroma plane it will read or write memory beyond the object's bounds. Fix by replacing the open-coded divisions with drm_format_info_plane_width() and drm_format_info_plane_height(), which use DIV_ROUND_UP() and match the calculation already used in framebuffer_check(). Fixes: 4c3dbb2c312c ("drm: Add GEM backed framebuffer library") Cc: stable@vger.kernel.org # v4.14+ Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Ashutosh Desai <ashutoshdesai993@gmail.com> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Link: https://patch.msgid.link/20260420013637.457751-1-ashutoshdesai993@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: drivers/gpu/drm/drm_gem_framebuffer_helper.c [Not merge bf39607c1614 and f2b816d78a94] Signed-off-by: Zhang Hongtao <zhanghongtao35@huawei.com> --- drivers/gpu/drm/drm_gem_framebuffer_helper.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c index 2810d4131411..42c396d47d51 100644 --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c @@ -158,8 +158,10 @@ drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file, return ERR_PTR(-EINVAL); for (i = 0; i < info->num_planes; i++) { - unsigned int width = mode_cmd->width / (i ? info->hsub : 1); - unsigned int height = mode_cmd->height / (i ? info->vsub : 1); + unsigned int width = i ? DIV_ROUND_UP(mode_cmd->width, info->hsub) : + mode_cmd->width; + unsigned int height = i ? DIV_ROUND_UP(mode_cmd->height, info->vsub) : + mode_cmd->height; unsigned int min_size; objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]); -- 2.43.0