From: Kuniyuki Iwashima kuniyu@amazon.com
[ 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@googlegroups.com Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Willem de Bruijn willemb@google.com Link: https://lore.kernel.org/r/20230524232934.50950-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/packet/af_packet.c | 4 ++-- net/packet/diag.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 2089da69da103..131c347bba56b 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3255,7 +3255,7 @@ 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) @@ -3273,7 +3273,7 @@ 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 d9f912ad23dfa..ecabf78d29b8e 100644 --- a/net/packet/diag.c +++ b/net/packet/diag.c @@ -142,7 +142,7 @@ 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);