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| author | Suresh Jayaraman <sjayaraman@suse.de> | 2009-09-30 10:53:48 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-01 21:15:46 +0200 |
| commit | 3bd0f0c763e497c8674b28e3df2732f48683dabd (patch) | |
| tree | fd3bb8635291ad8c0b4e302e40cc776fd1644ada /mm/swapfile.c | |
| parent | a112a71d45b5e40c3cf07371d20a4a5079a72610 (diff) | |
| download | lwn-3bd0f0c763e497c8674b28e3df2732f48683dabd.tar.gz lwn-3bd0f0c763e497c8674b28e3df2732f48683dabd.zip | |
swapfile: avoid NULL pointer dereference in swapon when s_bdev is NULL
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@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 4de7f02f820b..a1bc6b9af9a2 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1974,12 +1974,14 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 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); |