The patch titled
swapfile: avoid NULL pointer dereference in swapon when s_bdev is NULL
has been added to the -mm tree. Its filename is
swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: swapfile: avoid NULL pointer dereference in swapon when s_bdev is NULL
From: Suresh Jayaraman <sjayaraman@xxxxxxx>
While testing Swap over NFS patchset, I noticed an oops that was triggered
during swapon. Investigating further, the NULL pointer deference is due
to the SSD device check/optimization in the swapon code that assumes
s_bdev could never be NULL.
inode->i_sb->s_bdev could be NULL in a few cases. For e.g. one such case
is loopback NFS mount, there could be others as well. Fix this by
ensuring s_bdev is not NULL before we try to deference s_bdev.
Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff -puN mm/swapfile.c~swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null mm/swapfile.c
--- a/mm/swapfile.c~swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null
+++ a/mm/swapfile.c
@@ -1974,12 +1974,14 @@ SYSCALL_DEFINE2(swapon, const char __use
goto bad_swap;
}
- if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
- p->flags |= SWP_SOLIDSTATE;
- p->cluster_next = 1 + (random32() % p->highest_bit);
+ if (p->bdev) {
+ if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
+ p->flags |= SWP_SOLIDSTATE;
+ p->cluster_next = 1 + (random32() % p->highest_bit);
+ }
+ if (discard_swap(p) == 0)
+ p->flags |= SWP_DISCARDABLE;
}
- if (discard_swap(p) == 0)
- p->flags |= SWP_DISCARDABLE;
mutex_lock(&swapon_mutex);
spin_lock(&swap_lock);
_
Patches currently in -mm which might be from sjayaraman@xxxxxxx are
swapfile-avoid-null-pointer-dereference-in-swapon-when-s_bdev-is-null.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
