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authorNeilBrown <neilb@suse.com>2019-04-05 11:34:40 +1100
committerJ. Bruce Fields <bfields@redhat.com>2019-04-05 19:57:24 -0400
commitd58431eacb226222430940134d97bfd72f292fcd (patch)
tree92c165aeccfb3dcc3918746317774fef2ba0ac99 /net/sunrpc/cache.c
parent79a3aaa7b82e3106be97842dedfd8429248896e6 (diff)
downloadlinux-d58431eacb226222430940134d97bfd72f292fcd.tar.bz2
sunrpc: don't mark uninitialised items as VALID.
A recent commit added a call to cache_fresh_locked() when an expired item was found. The call sets the CACHE_VALID flag, so it is important that the item actually is valid. There are two ways it could be valid: 1/ If ->update has been called to fill in relevant content 2/ if CACHE_NEGATIVE is set, to say that content doesn't exist. An expired item that is waiting for an update will be neither. Setting CACHE_VALID will mean that a subsequent call to cache_put() will be likely to dereference uninitialised pointers. So we must make sure the item is valid, and we already have code to do that in try_to_negate_entry(). This takes the hash lock and so cannot be used directly, so take out the two lines that we need and use them. Now cache_fresh_locked() is certain to be called only on a valid item. Cc: stable@kernel.org # 2.6.35 Fixes: 4ecd55ea0742 ("sunrpc: fix cache_head leak due to queued request") Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc/cache.c')
-rw-r--r--net/sunrpc/cache.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 12bb23b8e0c5..261131dfa1f1 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -54,6 +54,7 @@ static void cache_init(struct cache_head *h, struct cache_detail *detail)
h->last_refresh = now;
}
+static inline int cache_is_valid(struct cache_head *h);
static void cache_fresh_locked(struct cache_head *head, time_t expiry,
struct cache_detail *detail);
static void cache_fresh_unlocked(struct cache_head *head,
@@ -105,6 +106,8 @@ static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,
if (cache_is_expired(detail, tmp)) {
hlist_del_init_rcu(&tmp->cache_list);
detail->entries --;
+ if (cache_is_valid(tmp) == -EAGAIN)
+ set_bit(CACHE_NEGATIVE, &tmp->flags);
cache_fresh_locked(tmp, 0, detail);
freeme = tmp;
break;