sunrpc: don't mark uninitialised items as VALID.
commit d58431ea 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. Fixes: 4ecd55ea ("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> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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