lkml.org 
[lkml]   [2014]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.12 33/72] net: unix: non blocking recvmsg() should not return -EINTR
Date
From: Eric Dumazet <edumazet@google.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

[ Upstream commit de1443916791d75fdd26becb116898277bb0273f ]

Some applications didn't expect recvmsg() on a non blocking socket
could return -EINTR. This possibility was added as a side effect
of commit b3ca9b02b00704 ("net: fix multithreaded signal handling in
unix recv routines").

To hit this bug, you need to be a bit unlucky, as the u->readlock
mutex is usually held for very small periods.

Fixes: b3ca9b02b00704 ("net: fix multithreaded signal handling in unix recv routines")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/unix/af_unix.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index d7c1ac621a90..c3975bcf725f 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1785,8 +1785,11 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
goto out;

err = mutex_lock_interruptible(&u->readlock);
- if (err) {
- err = sock_intr_errno(sock_rcvtimeo(sk, noblock));
+ if (unlikely(err)) {
+ /* recvmsg() in non blocking mode is supposed to return -EAGAIN
+ * sk_rcvtimeo is not honored by mutex_lock_interruptible()
+ */
+ err = noblock ? -EAGAIN : -ERESTARTSYS;
goto out;
}

@@ -1911,6 +1914,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
struct unix_sock *u = unix_sk(sk);
struct sockaddr_un *sunaddr = msg->msg_name;
int copied = 0;
+ int noblock = flags & MSG_DONTWAIT;
int check_creds = 0;
int target;
int err = 0;
@@ -1926,7 +1930,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
goto out;

target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
- timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT);
+ timeo = sock_rcvtimeo(sk, noblock);

/* Lock the socket to prevent queue disordering
* while sleeps in memcpy_tomsg
@@ -1938,8 +1942,11 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
}

err = mutex_lock_interruptible(&u->readlock);
- if (err) {
- err = sock_intr_errno(timeo);
+ if (unlikely(err)) {
+ /* recvmsg() in non blocking mode is supposed to return -EAGAIN
+ * sk_rcvtimeo is not honored by mutex_lock_interruptible()
+ */
+ err = noblock ? -EAGAIN : -ERESTARTSYS;
goto out;
}

--
1.9.2


\
 
 \ /
  Last update: 2014-04-18 16:41    [W:0.281 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site