Date:   Tue,  5 Mar 2019 09:31:26 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        bpf <bpf@...r.kernel.org>, syzbot <syzkaller@...glegroups.com>,
        "Björn Töpel" <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>
Subject: [PATCH net] xsk: fix potential crash in xsk_diag_put_umem()

Fixes two typos in xsk_diag_put_umem()

syzbot reported the following crash :

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7641 Comm: syz-executor946 Not tainted 5.0.0-rc7+ #95
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:xsk_diag_put_umem net/xdp/xsk_diag.c:71 [inline]
RIP: 0010:xsk_diag_fill net/xdp/xsk_diag.c:113 [inline]
RIP: 0010:xsk_diag_dump+0xdcb/0x13a0 net/xdp/xsk_diag.c:143
Code: 8d be c0 04 00 00 48 89 f8 48 c1 e8 03 42 80 3c 20 00 0f 85 39 04 00 00 49 8b 96 c0 04 00 00 48 8d 7a 14 48 89 f8 48 c1 e8 03 <42> 0f b6 0c 20 48 89 f8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85
RSP: 0018:ffff888090bcf2d8 EFLAGS: 00010203
RAX: 0000000000000002 RBX: ffff8880a0aacbc0 RCX: ffffffff86ffdc3c
RDX: 0000000000000000 RSI: ffffffff86ffdc70 RDI: 0000000000000014
RBP: ffff888090bcf438 R08: ffff88808e04a700 R09: ffffed1011c74174
R10: ffffed1011c74173 R11: ffff88808e3a0b9f R12: dffffc0000000000
R13: ffff888093a6d818 R14: ffff88808e365240 R15: ffff88808e3a0b40
FS:  00000000011ea880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 000000008fa13000 CR4: 00000000001406e0
Call Trace:
 netlink_dump+0x55d/0xfb0 net/netlink/af_netlink.c:2252
 __netlink_dump_start+0x5b4/0x7e0 net/netlink/af_netlink.c:2360
 netlink_dump_start include/linux/netlink.h:226 [inline]
 xsk_diag_handler_dump+0x1b2/0x250 net/xdp/xsk_diag.c:170
 __sock_diag_cmd net/core/sock_diag.c:232 [inline]
 sock_diag_rcv_msg+0x322/0x410 net/core/sock_diag.c:263
 netlink_rcv_skb+0x17a/0x460 net/netlink/af_netlink.c:2485
 sock_diag_rcv+0x2b/0x40 net/core/sock_diag.c:274
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x536/0x720 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1925
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:632
 sock_write_iter+0x27c/0x3e0 net/socket.c:923
 call_write_iter include/linux/fs.h:1863 [inline]
 do_iter_readv_writev+0x5e0/0x8e0 fs/read_write.c:680
 do_iter_write fs/read_write.c:956 [inline]
 do_iter_write+0x184/0x610 fs/read_write.c:937
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1001
 do_writev+0xf6/0x290 fs/read_write.c:1036
 __do_sys_writev fs/read_write.c:1109 [inline]
 __se_sys_writev fs/read_write.c:1106 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1106
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440139
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcc966cc18 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440139
RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000004 R11: 0000000000000246 R12: 00000000004019c0
R13: 0000000000401a50 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 460a3c24d0a656c9 ]---
RIP: 0010:xsk_diag_put_umem net/xdp/xsk_diag.c:71 [inline]
RIP: 0010:xsk_diag_fill net/xdp/xsk_diag.c:113 [inline]
RIP: 0010:xsk_diag_dump+0xdcb/0x13a0 net/xdp/xsk_diag.c:143
Code: 8d be c0 04 00 00 48 89 f8 48 c1 e8 03 42 80 3c 20 00 0f 85 39 04 00 00 49 8b 96 c0 04 00 00 48 8d 7a 14 48 89 f8 48 c1 e8 03 <42> 0f b6 0c 20 48 89 f8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85
RSP: 0018:ffff888090bcf2d8 EFLAGS: 00010203
RAX: 0000000000000002 RBX: ffff8880a0aacbc0 RCX: ffffffff86ffdc3c
RDX: 0000000000000000 RSI: ffffffff86ffdc70 RDI: 0000000000000014
RBP: ffff888090bcf438 R08: ffff88808e04a700 R09: ffffed1011c74174
R10: ffffed1011c74173 R11: ffff88808e3a0b9f R12: dffffc0000000000
R13: ffff888093a6d818 R14: ffff88808e365240 R15: ffff88808e3a0b40
FS:  00000000011ea880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d22000 CR3: 000000008fa13000 CR4: 00000000001406f0

Fixes: a36b38aa2af6 ("xsk: add sock_diag interface for AF_XDP")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
Cc: Björn Töpel <bjorn.topel@...el.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Magnus Karlsson <magnus.karlsson@...el.com>
---
 net/xdp/xsk_diag.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/xdp/xsk_diag.c b/net/xdp/xsk_diag.c
index 661d007c3b2887223ecf417e1fb6f970b50146e8..d5e06c8e0cbf9f30fdcdfb6a6ce65f7356c9d89e 100644
--- a/net/xdp/xsk_diag.c
+++ b/net/xdp/xsk_diag.c
@@ -68,9 +68,9 @@ static int xsk_diag_put_umem(const struct xdp_sock *xs, struct sk_buff *nlskb)
 	err = nla_put(nlskb, XDP_DIAG_UMEM, sizeof(du), &du);
 
 	if (!err && umem->fq)
-		err = xsk_diag_put_ring(xs->tx, XDP_DIAG_UMEM_FILL_RING, nlskb);
+		err = xsk_diag_put_ring(umem->fq, XDP_DIAG_UMEM_FILL_RING, nlskb);
 	if (!err && umem->cq) {
-		err = xsk_diag_put_ring(xs->tx, XDP_DIAG_UMEM_COMPLETION_RING,
+		err = xsk_diag_put_ring(umem->cq, XDP_DIAG_UMEM_COMPLETION_RING,
 					nlskb);
 	}
 	return err;
-- 
2.21.0.352.gf09ad66450-goog

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