From: Zack Rusin <zack.rusin@broadcom.com> stable inclusion from stable-v5.10.265 commit eb20f418933bea53375843b27b4022c1810be63b category: bugfix bugzilla: NA CVE: CVE-2026-74443 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit f4f1db96bfd68b81053693ba53405b6f510ac16c upstream. vmw_cmd_dma() locates the DMA suffix at (unsigned long) &cmd->body + header->size - sizeof(*suffix) without checking that header->size is large enough to contain both cmd->body and the suffix. An undersized header makes the suffix pointer underflow back into the previous command in the bounce buffer. The verifier later writes suffix->maximumOffset, clobbering verified fields of an already-relocated earlier command -- a TOCTOU on the device-visible command stream that lets one command rewrite another's GMR id, surface id, or other authenticated fields. Reject the command if the body is too small for the suffix to fit. Fixes: 4e4ddd477743 ("drm/vmwgfx: Fix queries if no dma buffer thrashing is occuring.") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4.7 Signed-off-by: Zack Rusin <zack.rusin@broadcom.com> Reviewed-by: Ian Forbes <ian.forbes@broadcom.com> Link: https://patch.msgid.link/20260505222728.519626-8-zack.rusin@broadcom.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ziming Du <duziming2@huawei.com> --- drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index 6e75adaae0bcd..2084b029920c3 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -1508,6 +1508,12 @@ static int vmw_cmd_dma(struct vmw_private *dev_priv, bool dirty; cmd = container_of(header, typeof(*cmd), header); + + if (unlikely(header->size < sizeof(cmd->body) + sizeof(*suffix))) { + VMW_DEBUG_USER("Illegal SVGA_3D_CMD_SURFACE_DMA size.\n"); + return -EINVAL; + } + suffix = (SVGA3dCmdSurfaceDMASuffix *)((unsigned long) &cmd->body + header->size - sizeof(*suffix)); -- 2.43.0