From: Neil Brown Date: Sat, 5 Aug 2006 19:14:29 +0000 (-0700) Subject: [PATCH] knfsd: fix race related problem when adding items to and svcrpc auth cache X-Git-Tag: v2.6.18-rc4~25 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f34931fdc78b4895553aaa33748939cc7697c99;p=linux-2.6 [PATCH] knfsd: fix race related problem when adding items to and svcrpc auth cache If we don't find the item we are lookng for, we allocate a new one, and then grab the lock again and search to see if it has been added while we did the alloc. If it had been added we need to 'cache_put' the newly created item that we are never going to use. But as it hasn't been initialised properly, putting it can cause an oops. So move the ->init call earlier to that it will always be fully initilised if we have to put it. Thanks to Philipp Matthias Hahn for reporting the problem. Signed-off-by: Neil Brown Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 7026b0866b..00cb388ece 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -71,7 +71,12 @@ struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail, new = detail->alloc(); if (!new) return NULL; + /* must fully initialise 'new', else + * we might get lose if we need to + * cache_put it soon. + */ cache_init(new); + detail->init(new, key); write_lock(&detail->hash_lock); @@ -85,7 +90,6 @@ struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail, return tmp; } } - detail->init(new, key); new->next = *head; *head = new; detail->entries++;