Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code
From: Rainer Weikusat <hidden>
Date: 2016-02-05 21:44:35
Also in:
lkml, stable
Subsystem:
networking [general], networking [unix sockets], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-02-08 · Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code · Eric Dumazet <hidden>
- 2016-02-07 · Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code · Rainer Weikusat <hidden>
- 2016-02-07 · Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code · Rainer Weikusat <hidden>
- 2016-02-07 · Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code · Rainer Weikusat <hidden>
- 2016-02-05 · Re: [V4.4-rc6 Regression] af_unix: Revert 'lock_interruptible' in stream receive code · Rainer Weikusat <hidden>
The present unix_stream_read_generic contains various code sequences of the form err = -EDISASTER; if (<test>) goto out; This has the unfortunate side effect of possibly causing the error code to bleed through to the final out: return copied ? : err; and then to be wrongly returned if no data was copied because the caller didn't supply a data buffer, as demonstrated by the program available at http://pad.lv/1540731 Change it such that err is only set if an error condition was detected. Signed-off-by: Rainer Weikusat <redacted> ---
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 49d5093..138787d 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c@@ -2277,13 +2277,15 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state) size_t size = state->size; unsigned int last_len; - err = -EINVAL; - if (sk->sk_state != TCP_ESTABLISHED) + if (sk->sk_state != TCP_ESTABLISHED) { + err = -EINVAL; goto out; + } - err = -EOPNOTSUPP; - if (flags & MSG_OOB) + if (flags & MSG_OOB) { + err = -EOPNOTSUPP; goto out; + } target = sock_rcvlowat(sk, flags & MSG_WAITALL, size); timeo = sock_rcvtimeo(sk, noblock);
@@ -2329,9 +2331,11 @@ again: goto unlock; unix_state_unlock(sk); - err = -EAGAIN; - if (!timeo) + if (!timeo) { + err = -EAGAIN; break; + } + mutex_unlock(&u->readlock); timeo = unix_stream_data_wait(sk, timeo, last,