David, Looks good to me.
You can add a Reviewed-by line.
Thanks.
Jeffrey Altman
On 8/9/2019 5:47 PM, David Howells wrote:
> 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+20dee719a2e090427...@syzkaller.appspotmail.com
> Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting")
> Signed-off-by: David Howells <dhowe...@redhat.com>
> cc: Jeffrey Altman <jalt...@auristor.com>
> ---
>
> net/rxrpc/local_object.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> 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);
> + }
> }
>
> /*
>
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