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authorSuresh Jayaraman <sjayaraman@suse.de>2009-09-30 10:53:48 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-10-01 21:15:46 +0200
commit3bd0f0c763e497c8674b28e3df2732f48683dabd (patch)
treefd3bb8635291ad8c0b4e302e40cc776fd1644ada
parenta112a71d45b5e40c3cf07371d20a4a5079a72610 (diff)
downloadlinux-2.6.34-ux500-3bd0f0c763e497c8674b28e3df2732f48683dabd.tar.gz
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>
-rw-r--r--mm/swapfile.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 4de7f02f820..a1bc6b9af9a 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);