]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
mm: enforce min addr even if capable() in expand_downwards()
authorJann Horn <jannh@google.com>
Wed, 27 Feb 2019 20:29:52 +0000 (21:29 +0100)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 28 Feb 2019 01:27:02 +0000 (17:27 -0800)
commit0a1d52994d440e21def1c2174932410b4f2a98a1
tree0674c4cb793d0402ce24061f8db61d04024d1a88
parent7d762d69145a54d169f58e56d6dac57a5508debc
mm: enforce min addr even if capable() in expand_downwards()

security_mmap_addr() does a capability check with current_cred(), but
we can reach this code from contexts like a VFS write handler where
current_cred() must not be used.

This can be abused on systems without SMAP to make NULL pointer
dereferences exploitable again.

Fixes: 8869477a49c3 ("security: protect from stack expansion into low vm addresses")
Cc: stable@kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mmap.c