From 68553f1a6f746bf860bce3eb42d78c26a717d9c0 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 9 Aug 2019 22:47:47 +0100 Subject: rxrpc: Fix local refcounting Fix rxrpc_unuse_local() to handle a NULL local pointer as it can be called on an unbound socket on which rx->local is not yet set. The following reproduced (includes omitted): int main(void) { socket(AF_RXRPC, SOCK_DGRAM, AF_INET); return 0; } causes the following oops to occur: BUG: kernel NULL pointer dereference, address: 0000000000000010 ... RIP: 0010:rxrpc_unuse_local+0x8/0x1b ... Call Trace: rxrpc_release+0x2b5/0x338 __sock_release+0x37/0xa1 sock_close+0x14/0x17 __fput+0x115/0x1e9 task_work_run+0x72/0x98 do_exit+0x51b/0xa7a ? __context_tracking_exit+0x4e/0x10e do_group_exit+0xab/0xab __x64_sys_exit_group+0x14/0x17 do_syscall_64+0x89/0x1d4 entry_SYSCALL_64_after_hwframe+0x49/0xbe Reported-by: syzbot+20dee719a2e090427b5f@syzkaller.appspotmail.com Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting") Signed-off-by: David Howells cc: Jeffrey Altman Signed-off-by: David S. Miller --- net/rxrpc/local_object.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'net/rxrpc/local_object.c') diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c index 9798159ee65f..c9db3e762d8d 100644 --- a/net/rxrpc/local_object.c +++ b/net/rxrpc/local_object.c @@ -402,11 +402,13 @@ void rxrpc_unuse_local(struct rxrpc_local *local) { unsigned int au; - au = atomic_dec_return(&local->active_users); - if (au == 0) - rxrpc_queue_local(local); - else - rxrpc_put_local(local); + if (local) { + au = atomic_dec_return(&local->active_users); + if (au == 0) + rxrpc_queue_local(local); + else + rxrpc_put_local(local); + } } /* -- cgit v1.2.3-59-g8ed1b