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  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Date:   Thu, 16 Jan 2020 12:04:00 -0500
From:   Sasha Levin <>
Cc:     Magnus Karlsson <>,
        Kal Cutter Conley <>,
        Alexei Starovoitov <>,
        Jonathan Lemon <>,
        Sasha Levin <>,,
Subject: [PATCH AUTOSEL 4.19 602/671] xsk: Fix registration of Rx-only sockets

From: Magnus Karlsson <>

[ Upstream commit 2afd23f78f39da84937006ecd24aa664a4ab052b ]

Having Rx-only AF_XDP sockets can potentially lead to a crash in the
system by a NULL pointer dereference in xsk_umem_consume_tx(). This
function iterates through a list of all sockets tied to a umem and
checks if there are any packets to send on the Tx ring. Rx-only
sockets do not have a Tx ring, so this will cause a NULL pointer
dereference. This will happen if you have registered one or more
Rx-only sockets to a umem and the driver is checking the Tx ring even
on Rx, or if the XDP_SHARED_UMEM mode is used and there is a mix of
Rx-only and other sockets tied to the same umem.

Fixed by only putting sockets with a Tx component on the list that
xsk_umem_consume_tx() iterates over.

Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions")
Reported-by: Kal Cutter Conley <>
Signed-off-by: Magnus Karlsson <>
Signed-off-by: Alexei Starovoitov <>
Acked-by: Jonathan Lemon <>
Signed-off-by: Sasha Levin <>
 net/xdp/xdp_umem.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index d9117ab035f7..556a649512b6 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -23,6 +23,9 @@ void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
 	unsigned long flags;
+	if (!xs->tx)
+		return;
 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
 	list_add_rcu(&xs->list, &umem->xsk_list);
 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
@@ -32,6 +35,9 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
 	unsigned long flags;
+	if (!xs->tx)
+		return;
 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);

Powered by blists - more mailing lists