@@ -129,6 +129,13 @@ 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) {
@@ -403,7 +410,7 @@ 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;
}
This is a note to let you know that I have just added a patch titled nfsd: when reusing an existing repcache entry, unhash it first to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 4e7dbfd74938fec7ce7575f308519830c644e8b3 Mon Sep 17 00:00:00 2001 From: Jeff Layton <jlayton@redhat.com> Date: Mon, 2 Dec 2013 15:26:19 -0500 Subject: nfsd: when reusing an existing repcache entry, unhash it first commit 781c2a5a5f75eacc04663aced0f0f1a648d4f308 upstream. 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. 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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/nfsd/nfscache.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) -- 1.8.3.2