Commit 7dc0850c authored by NeilBrown's avatar NeilBrown Committed by Xponential31
Browse files

sunrpc: don't mark uninitialised items as VALID. 



commit d58431eacb226222430940134d97bfd72f292fcd upstream.

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: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cd2492b0

net/sunrpc/cache.c

+3 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ static void cache_init(struct cache_head *h) 
	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);

static void cache_fresh_unlocked(struct cache_head *head,

				struct cache_detail *detail);
@@ -98,6 +99,8 @@ struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail, 
				*hp = tmp->next;

				tmp->next = NULL;

				detail->entries --;

				if (cache_is_valid(tmp) == -EAGAIN)

					set_bit(CACHE_NEGATIVE, &tmp->flags);

				cache_fresh_locked(tmp, 0);

				freeme = tmp;

				break;