| From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 256/273] af_unix: Don't set err in unix_stream_read_generic unless there was an error | Date | Mon, 7 Mar 2016 14:50:47 -0800 |
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4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Rainer Weikusat <rweikusat@mobileactivedefense.com>
commit 1b92ee3d03af6643df395300ba7748f19ecdb0c5 upstream.
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.
Fixes: 3822b5c2fc62 ("af_unix: Revert 'lock_interruptible' in stream receive code") Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com> Signed-off-by: Rainer Weikusat <rweikusat@mobileactivedefense.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/unix/af_unix.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index b5f9049..18a0116 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2274,13 +2274,15 @@ 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 (unlikely(sk->sk_state != TCP_ESTABLISHED)) { + err = -EINVAL; goto out; + } - err = -EOPNOTSUPP; - if (flags & MSG_OOB) + if (unlikely(flags & MSG_OOB)) { + err = -EOPNOTSUPP; goto out; + } target = sock_rcvlowat(sk, flags & MSG_WAITALL, size); timeo = sock_rcvtimeo(sk, noblock); @@ -2326,9 +2328,11 @@ 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, -- 2.7.0
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