This is a note to let you know that I've just added the patch titled
af_packet: Fix data-races of pkt_sk(sk)->num.
to the 5.4-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:
af_packet-fix-data-races-of-pkt_sk-sk-num.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0f719b98ebf17fda632a2497c97b42dc2e3dc70f
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Wed May 24 16:29:34 2023 -0700
af_packet: Fix data-races of pkt_sk(sk)->num.
[ Upstream commit 822b5a1c17df7e338b9f05d1cfe5764e37c7f74f ]
syzkaller found a data race of pkt_sk(sk)->num.
The value is changed under lock_sock() and po->bind_lock, so we
need READ_ONCE() to access pkt_sk(sk)->num without these locks in
packet_bind_spkt(), packet_bind(), and sk_diag_fill().
Note that WRITE_ONCE() is already added by commit c7d2ef5dd4b0
("net/packet: annotate accesses to po->bind").
BUG: KCSAN: data-race in packet_bind / packet_do_bind
write (marked) to 0xffff88802ffd1cee of 2 bytes by task 7322 on cpu 0:
packet_do_bind+0x446/0x640 net/packet/af_packet.c:3236
packet_bind+0x99/0xe0 net/packet/af_packet.c:3321
__sys_bind+0x19b/0x1e0 net/socket.c:1803
__do_sys_bind net/socket.c:1814 [inline]
__se_sys_bind net/socket.c:1812 [inline]
__x64_sys_bind+0x40/0x50 net/socket.c:1812
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc
read to 0xffff88802ffd1cee of 2 bytes by task 7318 on cpu 1:
packet_bind+0xbf/0xe0 net/packet/af_packet.c:3322
__sys_bind+0x19b/0x1e0 net/socket.c:1803
__do_sys_bind net/socket.c:1814 [inline]
__se_sys_bind net/socket.c:1812 [inline]
__x64_sys_bind+0x40/0x50 net/socket.c:1812
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc
value changed: 0x0300 -> 0x0000
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7318 Comm: syz-executor.4 Not tainted 6.3.0-13380-g7fddb5b5300c #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Fixes: 96ec6327144e ("packet: Diag core and basic socket info dumping")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzkaller <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230524232934.50950-1-kuniyu@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7a940f2f30671..2d4cc53180a1c 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3230,7 +3230,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));
name[sizeof(uaddr->sa_data)] = 0;
- return packet_do_bind(sk, name, 0, pkt_sk(sk)->num);
+ return packet_do_bind(sk, name, 0, READ_ONCE(pkt_sk(sk)->num));
}
static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -3248,7 +3248,7 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len
return -EINVAL;
return packet_do_bind(sk, NULL, sll->sll_ifindex,
- sll->sll_protocol ? : pkt_sk(sk)->num);
+ sll->sll_protocol ? : READ_ONCE(pkt_sk(sk)->num));
}
static struct proto packet_proto = {
diff --git a/net/packet/diag.c b/net/packet/diag.c
index d704c7bf51b20..a68a84574c739 100644
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -143,7 +143,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
rp = nlmsg_data(nlh);
rp->pdiag_family = AF_PACKET;
rp->pdiag_type = sk->sk_type;
- rp->pdiag_num = ntohs(po->num);
+ rp->pdiag_num = ntohs(READ_ONCE(po->num));
rp->pdiag_ino = sk_ino;
sock_diag_save_cookie(sk, rp->pdiag_cookie);
