Patch "netfilter: drop outermost socket lock in getsockopt()" has been added to the 4.15-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    netfilter: drop outermost socket lock in getsockopt()

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-drop-outermost-socket-lock-in-getsockopt.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 01ea306f2ac2baff98d472da719193e738759d93 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Thu, 8 Feb 2018 12:19:00 +0100
Subject: netfilter: drop outermost socket lock in getsockopt()

From: Paolo Abeni <pabeni@xxxxxxxxxx>

commit 01ea306f2ac2baff98d472da719193e738759d93 upstream.

The Syzbot reported a possible deadlock in the netfilter area caused by
rtnl lock, xt lock and socket lock being acquired with a different order
on different code paths, leading to the following backtrace:
Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>

======================================================
WARNING: possible circular locking dependency detected
4.15.0+ #301 Not tainted
------------------------------------------------------
syzkaller233489/4179 is trying to acquire lock:
  (rtnl_mutex){+.+.}, at: [<0000000048e996fd>] rtnl_lock+0x17/0x20
net/core/rtnetlink.c:74

but task is already holding lock:
  (&xt[i].mutex){+.+.}, at: [<00000000328553a2>]
xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041

which lock already depends on the new lock.
===

Since commit 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock
only in the required scope"), we already acquire the socket lock in
the innermost scope, where needed. In such commit I forgot to remove
the outer-most socket lock from the getsockopt() path, this commit
addresses the issues dropping it now.

v1 -> v2: fix bad subj, added relavant 'fixes' tag

Fixes: 22265a5c3c10 ("netfilter: xt_TEE: resolve oif using netdevice notifiers")
Fixes: 202f59afd441 ("netfilter: ipt_CLUSTERIP: do not hold dev")
Fixes: 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock only in the required scope")
Reported-by: syzbot+ddde1c7b7ff7442d7f2d@xxxxxxxxxxxxxxxxxxxxxxxxx
Suggested-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/ipv4/ip_sockglue.c   |    7 +------
 net/ipv6/ipv6_sockglue.c |   10 ++--------
 2 files changed, 3 insertions(+), 14 deletions(-)

--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1563,10 +1563,7 @@ int ip_getsockopt(struct sock *sk, int l
 		if (get_user(len, optlen))
 			return -EFAULT;
 
-		lock_sock(sk);
-		err = nf_getsockopt(sk, PF_INET, optname, optval,
-				&len);
-		release_sock(sk);
+		err = nf_getsockopt(sk, PF_INET, optname, optval, &len);
 		if (err >= 0)
 			err = put_user(len, optlen);
 		return err;
@@ -1598,9 +1595,7 @@ int compat_ip_getsockopt(struct sock *sk
 		if (get_user(len, optlen))
 			return -EFAULT;
 
-		lock_sock(sk);
 		err = compat_nf_getsockopt(sk, PF_INET, optname, optval, &len);
-		release_sock(sk);
 		if (err >= 0)
 			err = put_user(len, optlen);
 		return err;
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -1367,10 +1367,7 @@ int ipv6_getsockopt(struct sock *sk, int
 		if (get_user(len, optlen))
 			return -EFAULT;
 
-		lock_sock(sk);
-		err = nf_getsockopt(sk, PF_INET6, optname, optval,
-				&len);
-		release_sock(sk);
+		err = nf_getsockopt(sk, PF_INET6, optname, optval, &len);
 		if (err >= 0)
 			err = put_user(len, optlen);
 	}
@@ -1409,10 +1406,7 @@ int compat_ipv6_getsockopt(struct sock *
 		if (get_user(len, optlen))
 			return -EFAULT;
 
-		lock_sock(sk);
-		err = compat_nf_getsockopt(sk, PF_INET6,
-					   optname, optval, &len);
-		release_sock(sk);
+		err = compat_nf_getsockopt(sk, PF_INET6, optname, optval, &len);
 		if (err >= 0)
 			err = put_user(len, optlen);
 	}


Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are

queue-4.15/netfilter-drop-outermost-socket-lock-in-getsockopt.patch



[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]