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rxrpc: Fix use-after-free in rxrpc_put_local() 

Fix rxrpc_put_local() to not access local->debug_id after calling
atomic_dec_return() as, unless that returned n==0, we no longer have the
right to access the object.

Fixes: 06d9532fa6 ("rxrpc: Fix read-after-free in rxrpc_queue_local()")
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2020-01-30 21:50:35 +00:00
parent 9fbf082f56
commit fac20b9e73
1 changed files with 4 additions and 1 deletions
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5
net/rxrpc/local_object.c
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@ -364,11 +364,14 @@ void rxrpc_queue_local(struct rxrpc_local *local)
void rxrpc_put_local(struct rxrpc_local *local)
{
const void *here = __builtin_return_address(0);
unsigned int debug_id;
int n;
if (local) {
debug_id = local->debug_id;
n = atomic_dec_return(&local->usage);
trace_rxrpc_local(local->debug_id, rxrpc_local_put, n, here);
trace_rxrpc_local(debug_id, rxrpc_local_put, n, here);
if (n == 0)
call_rcu(&local->rcu, rxrpc_local_rcu);