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| author | Abhijith Das <adas@redhat.com> | 2012-12-19 10:48:01 -0500 |
|---|---|---|
| committer | Steven Whitehouse <swhiteho@redhat.com> | 2013-01-02 10:04:53 +0000 |
| commit | f1213cacc7ffc7d4cdef3692f22b28a2df3216f5 (patch) | |
| tree | 323a502b74dc45a726b05c5b0bddccb77ba516df | |
| parent | ec1487528bed94c4aaff3687834fe94203880fd6 (diff) | |
| download | linux-stable-f1213cacc7ffc7d4cdef3692f22b28a2df3216f5.tar.gz linux-stable-f1213cacc7ffc7d4cdef3692f22b28a2df3216f5.tar.bz2 linux-stable-f1213cacc7ffc7d4cdef3692f22b28a2df3216f5.zip | |
GFS2: Fix race in gfs2_rs_alloc
QE aio tests uncovered a race condition in gfs2_rs_alloc where it's possible
to come out of the function with a valid ip->i_res allocation but it gets
freed before use resulting in a NULL ptr dereference.
This patch envelopes the initial short-circuit check for non-NULL ip->i_res
into the mutex lock. With this patch, I was able to successfully run the
reproducer test multiple times.
Resolves: rhbz#878476
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
| -rw-r--r-- | fs/gfs2/rgrp.c | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index 37ee061d899e..738b3888adc6 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -557,22 +557,20 @@ void gfs2_free_clones(struct gfs2_rgrpd *rgd) */ int gfs2_rs_alloc(struct gfs2_inode *ip) { - struct gfs2_blkreserv *res; + int error = 0; + down_write(&ip->i_rw_mutex); if (ip->i_res) - return 0; - - res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS); - if (!res) - return -ENOMEM; + goto out; - RB_CLEAR_NODE(&res->rs_node); + ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS); + if (!ip->i_res) { + error = -ENOMEM; + goto out; + } - down_write(&ip->i_rw_mutex); - if (ip->i_res) - kmem_cache_free(gfs2_rsrv_cachep, res); - else - ip->i_res = res; + RB_CLEAR_NODE(&ip->i_res->rs_node); +out: up_write(&ip->i_rw_mutex); return 0; } |