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authorJeff Layton <jlayton@redhat.com>2013-12-02 15:26:19 -0500
committerJ. Bruce Fields <bfields@redhat.com>2013-12-10 20:34:44 -0500
commit781c2a5a5f75eacc04663aced0f0f1a648d4f308 (patch)
treed99f1c5131cf632a13096f10dbd54c43618c5872 /fs/nfsd
parent374b105797c3d4f29c685f3be535c35f5689b30e (diff)
nfsd: when reusing an existing repcache entry, unhash it first
The DRC code will attempt to reuse an existing, expired cache entry in preference to allocating a new one. It'll then search the cache, and if it gets a hit it'll then free the cache entry that it was going to reuse. The cache code doesn't unhash the entry that it's going to reuse however, so it's possible for it end up designating an entry for reuse and then subsequently freeing the same entry after it finds it. This leads it to a later use-after-free situation and usually some list corruption warnings or an oops. Fix this by simply unhashing the entry that we intend to reuse. That will mean that it's not findable via a search and should prevent this situation from occurring. Cc: stable@vger.kernel.org # v3.10+ Reported-by: Christoph Hellwig <hch@infradead.org> Reported-by: g. artim <gartim@gmail.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfscache.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 9186c7ce0b14..b6af150c96b8 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -132,6 +132,13 @@ nfsd_reply_cache_alloc(void)
}
static void
+nfsd_reply_cache_unhash(struct svc_cacherep *rp)
+{
+ hlist_del_init(&rp->c_hash);
+ list_del_init(&rp->c_lru);
+}
+
+static void
nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
{
if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
@@ -417,7 +424,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
rp = list_first_entry(&lru_head, struct svc_cacherep, c_lru);
if (nfsd_cache_entry_expired(rp) ||
num_drc_entries >= max_drc_entries) {
- lru_put_end(rp);
+ nfsd_reply_cache_unhash(rp);
prune_cache_entries();
goto search_cache;
}