mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 08:19:28 +00:00
RPC: Fix two potential races in put_rpccred
It is possible for rpcauth_destroy_credcache() to cause the rpc credentials to be unhashed while put_rpccred is waiting for the rpc_credcache_lock on another cpu. Should this happen, then we can end up calling hlist_del_rcu(&cred->cr_hash) a second time in put_rpccred, thus causing list corruption. Should the credential actually be hashed, it is also possible for rpcauth_lookup_credcache to find and reference it before we get round to unhashing it. In this case, the call to rpcauth_unhash_cred will fail, and so we should just exit without destroying the cred. Reported-by: Neil Brown <neilb@suse.de> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
parent
feb8ca37cc
commit
f0380f3d16
1 changed files with 23 additions and 16 deletions
|
@ -123,16 +123,19 @@ rpcauth_unhash_cred_locked(struct rpc_cred *cred)
|
|||
clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
|
||||
}
|
||||
|
||||
static void
|
||||
static int
|
||||
rpcauth_unhash_cred(struct rpc_cred *cred)
|
||||
{
|
||||
spinlock_t *cache_lock;
|
||||
int ret;
|
||||
|
||||
cache_lock = &cred->cr_auth->au_credcache->lock;
|
||||
spin_lock(cache_lock);
|
||||
if (atomic_read(&cred->cr_count) == 0)
|
||||
ret = atomic_read(&cred->cr_count) == 0;
|
||||
if (ret)
|
||||
rpcauth_unhash_cred_locked(cred);
|
||||
spin_unlock(cache_lock);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
|
@ -446,31 +449,35 @@ void
|
|||
put_rpccred(struct rpc_cred *cred)
|
||||
{
|
||||
/* Fast path for unhashed credentials */
|
||||
if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
|
||||
goto need_lock;
|
||||
|
||||
if (!atomic_dec_and_test(&cred->cr_count))
|
||||
if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
|
||||
if (atomic_dec_and_test(&cred->cr_count))
|
||||
cred->cr_ops->crdestroy(cred);
|
||||
return;
|
||||
goto out_destroy;
|
||||
need_lock:
|
||||
}
|
||||
|
||||
if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
|
||||
return;
|
||||
if (!list_empty(&cred->cr_lru)) {
|
||||
number_cred_unused--;
|
||||
list_del_init(&cred->cr_lru);
|
||||
}
|
||||
if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
|
||||
rpcauth_unhash_cred(cred);
|
||||
if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
|
||||
cred->cr_expire = jiffies;
|
||||
list_add_tail(&cred->cr_lru, &cred_unused);
|
||||
number_cred_unused++;
|
||||
spin_unlock(&rpc_credcache_lock);
|
||||
return;
|
||||
if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
|
||||
cred->cr_expire = jiffies;
|
||||
list_add_tail(&cred->cr_lru, &cred_unused);
|
||||
number_cred_unused++;
|
||||
goto out_nodestroy;
|
||||
}
|
||||
if (!rpcauth_unhash_cred(cred)) {
|
||||
/* We were hashed and someone looked us up... */
|
||||
goto out_nodestroy;
|
||||
}
|
||||
}
|
||||
spin_unlock(&rpc_credcache_lock);
|
||||
out_destroy:
|
||||
cred->cr_ops->crdestroy(cred);
|
||||
return;
|
||||
out_nodestroy:
|
||||
spin_unlock(&rpc_credcache_lock);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(put_rpccred);
|
||||
|
||||
|
|
Loading…
Reference in a new issue