swapfile: fix memory corruption via malformed swapfile
authorJann Horn <jann@thejh.net>
Thu, 10 Nov 2016 18:46:19 +0000 (10:46 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 11 Nov 2016 16:12:37 +0000 (08:12 -0800)
commitdd111be69114cc867f8e826284559bfbc1c40e37
treebd245104ef2c79a3aaa1fe61ff3c2c6a13744736
parent6b36ba599d602d8a73920fb5c470fe272fac49c1
swapfile: fix memory corruption via malformed swapfile

When root activates a swap partition whose header has the wrong
endianness, nr_badpages elements of badpages are swabbed before
nr_badpages has been checked, leading to a buffer overrun of up to 8GB.

This normally is not a security issue because it can only be exploited
by root (more specifically, a process with CAP_SYS_ADMIN or the ability
to modify a swap file/partition), and such a process can already e.g.
modify swapped-out memory of any other userspace process on the system.

Link: http://lkml.kernel.org/r/1477949533-2509-1-git-send-email-jann@thejh.net
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/swapfile.c