tree 4a6833bd11235602d4c8986c77bfa35936b98fd3
parent 626b2dda7651a7c766108db4cdc0825db05b980d
author Mathias Krause <minipli@grsecurity.net> 1643272459 +1000
committer Linus Torvalds <torvalds@linux-foundation.org> 1643298920 +0200

drm/vmwgfx: Fix stale file descriptors on failed usercopy

A failing usercopy of the fence_rep object will lead to a stale entry in
the file descriptor table as put_unused_fd() won't release it. This
enables userland to refer to a dangling 'file' object through that still
valid file descriptor, leading to all kinds of use-after-free
exploitation scenarios.

Fix this by deferring the call to fd_install() until after the usercopy
has succeeded.

Fixes: c906965dee22 ("drm/vmwgfx: Add export fence to file descriptor support")
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>