diff options
| author | Jann Horn <jann@thejh.net> | 2016-11-10 10:46:19 -0800 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-04-11 10:58:02 +0200 |
| commit | 73c2bebf9b78c638d58f4e8a58a84c2bd0363b02 (patch) | |
| tree | d63608862c3cc4ea3b52c420b812aa09c8d43feb | |
| parent | bab4ca686040ea785f77d6e52eaf589b94c9d41b (diff) | |
swapfile: fix memory corruption via malformed swapfile
commit dd111be69114cc867f8e826284559bfbc1c40e37 upstream.
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -rw-r--r-- | mm/swapfile.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index e22ee2292..e732fe3c7 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2126,6 +2126,8 @@ static unsigned long read_swap_header(struct swap_info_struct *p, swab32s(&swap_header->info.version); swab32s(&swap_header->info.last_page); swab32s(&swap_header->info.nr_badpages); + if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) + return 0; for (i = 0; i < swap_header->info.nr_badpages; i++) swab32s(&swap_header->info.badpages[i]); } |