lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Sat, 12 Dec 2015 11:33:16 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Vegard Nossum <vegard.nossum@...cle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Santosh Shilimkar <santosh.shilimkar@...cle.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: [PATCH 4.1 21/45] RDS: fix race condition when sending a message on unbound socket

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

------------------

From: Quentin Casasnovas <quentin.casasnovas@...cle.com>

[ Upstream commit 8c7188b23474cca017b3ef354c4a58456f68303a ]

Sasha's found a NULL pointer dereference in the RDS connection code when
sending a message to an apparently unbound socket.  The problem is caused
by the code checking if the socket is bound in rds_sendmsg(), which checks
the rs_bound_addr field without taking a lock on the socket.  This opens a
race where rs_bound_addr is temporarily set but where the transport is not
in rds_bind(), leading to a NULL pointer dereference when trying to
dereference 'trans' in __rds_conn_create().

Vegard wrote a reproducer for this issue, so kindly ask him to share if
you're interested.

I cannot reproduce the NULL pointer dereference using Vegard's reproducer
with this patch, whereas I could without.

Complete earlier incomplete fix to CVE-2015-6937:

  74e98eb08588 ("RDS: verify the underlying transport exists before creating a connection")

Cc: David S. Miller <davem@...emloft.net>
Cc: stable@...r.kernel.org

Reviewed-by: Vegard Nossum <vegard.nossum@...cle.com>
Reviewed-by: Sasha Levin <sasha.levin@...cle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@...cle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/rds/connection.c |    6 ------
 net/rds/send.c       |    4 +++-
 2 files changed, 3 insertions(+), 7 deletions(-)

--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -187,12 +187,6 @@ new_conn:
 		}
 	}
 
-	if (trans == NULL) {
-		kmem_cache_free(rds_conn_slab, conn);
-		conn = ERR_PTR(-ENODEV);
-		goto out;
-	}
-
 	conn->c_trans = trans;
 
 	ret = trans->conn_alloc(conn, gfp);
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -986,11 +986,13 @@ int rds_sendmsg(struct socket *sock, str
 		release_sock(sk);
 	}
 
-	/* racing with another thread binding seems ok here */
+	lock_sock(sk);
 	if (daddr == 0 || rs->rs_bound_addr == 0) {
+		release_sock(sk);
 		ret = -ENOTCONN; /* XXX not a great errno */
 		goto out;
 	}
+	release_sock(sk);
 
 	/* size of rm including all sgs */
 	ret = rds_rm_size(msg, payload_len);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists