In the Linux kernel, the following vulnerability has been resolved:
drm/vmwgfx: validate DRAW_PRIMITIVES header size before division
vmw_cmd_draw() computes
maxnum = (header->size - sizeof(cmd->body)) / sizeof(*decl);
where header->size is u32 and is taken straight from the user-supplied command stream. When header->size is less than sizeof(cmd->body) the unsigned subtraction wraps to nearly 4 GiB, producing a huge maxnum. Any user-controlled cmd->body.numVertexDecls then passes the bound and the loop dereferences decl[i] far past the end of the kernel command bounce buffer, producing an out-of-bounds read of kernel memory.
Reject undersized headers up front.
References
- https://git.kernel.org/stable/c/2666cddf0dd218aa9bd1f99db688d1b532eac21a
- https://git.kernel.org/stable/c/85891d174707d8bddcec7a888fb4e1d17def34f3
- https://git.kernel.org/stable/c/c77cf8edae2bd3a1599115301cc7c98d0c78e731
- https://git.kernel.org/stable/c/dc0be7662b7b0ce28cb5eea864737793ed7b9e70
- https://git.kernel.org/stable/c/fc0c02f510e41650df3479f96e257acf87d8a20a