From: David Howells dhowells@redhat.com
[ Upstream commit b13023421b5179413421333f602850914f6a7ad8 ]
In rxrpc_destroy_all_calls(), there are two phases: (1) make sure the ->calls list is empty, emitting error messages if not, and (2) wait for the RCU cleanup to happen on outstanding calls (ie. ->nr_calls becomes 0).
To avoid taking the call_lock, the function prechecks ->calls and if empty, it returns to avoid taking the lock - this is wrong, however: it still needs to go and do the second phase and wait for ->nr_calls to become 0.
Without this, the rxrpc_net struct may get deallocated before we get to the RCU cleanup for the last calls. This can lead to:
Slab corruption (Not tainted): kmalloc-16k start=ffff88802b178000, len=16384 050: 6b 6b 6b 6b 6b 6b 6b 6b 61 6b 6b 6b 6b 6b 6b 6b kkkkkkkkakkkkkkk
Note the "61" at offset 0x58. This corresponds to the ->nr_calls member of struct rxrpc_net (which is >9k in size, and thus allocated out of the 16k slab).
Fix this by flipping the condition on the if-statement, putting the locked section inside the if-body and dropping the return from there. The function will then always go on to wait for the RCU cleanup on outstanding calls.
Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing") Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/rxrpc/call_object.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-)
--- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -701,30 +701,30 @@ void rxrpc_destroy_all_calls(struct rxrp
_enter("");
- if (list_empty(&rxnet->calls)) - return; - - write_lock(&rxnet->call_lock); + if (!list_empty(&rxnet->calls)) { + write_lock(&rxnet->call_lock);
- while (!list_empty(&rxnet->calls)) { - call = list_entry(rxnet->calls.next, struct rxrpc_call, link); - _debug("Zapping call %p", call); - - rxrpc_see_call(call); - list_del_init(&call->link); - - pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n", - call, atomic_read(&call->usage), - rxrpc_call_states[call->state], - call->flags, call->events); + while (!list_empty(&rxnet->calls)) { + call = list_entry(rxnet->calls.next, + struct rxrpc_call, link); + _debug("Zapping call %p", call); + + rxrpc_see_call(call); + list_del_init(&call->link); + + pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n", + call, atomic_read(&call->usage), + rxrpc_call_states[call->state], + call->flags, call->events); + + write_unlock(&rxnet->call_lock); + cond_resched(); + write_lock(&rxnet->call_lock); + }
write_unlock(&rxnet->call_lock); - cond_resched(); - write_lock(&rxnet->call_lock); }
- write_unlock(&rxnet->call_lock); - atomic_dec(&rxnet->nr_calls); wait_var_event(&rxnet->nr_calls, !atomic_read(&rxnet->nr_calls)); }