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[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 <pmhahn@svs.Informatik.Uni-Oldenburg.de>
for reporting the problem.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Neil Brown 2006-08-05 12:14:29 -07:00 committed by Linus Torvalds
parent 9b7f750d44
commit 2f34931fdc
1 changed files with 5 additions and 1 deletions
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6
net/sunrpc/cache.c
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@ -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++;