"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue\n\nFix NULL pointer data-races in sk_psock_skb_ingress_enqueue() which\nsyzbot reported [1].\n\n[1]\nBUG: KCSAN: data-race in sk_psock_drop / sk_psock_skb_ingress_enqueue\n\nwrite to 0xffff88814b3278b8 of 8 bytes by task 10724 on cpu 1:\n sk_psock_stop_verdict net/core/skmsg.c:1257 [inline]\n sk_psock_drop+0x13e/0x1f0 net/core/skmsg.c:843\n sk_psock_put include/linux/skmsg.h:459 [inline]\n sock_map_close+0x1a7/0x260 net/core/sock_map.c:1648\n unix_release+0x4b/0x80 net/unix/af_unix.c:1048\n __sock_release net/socket.c:659 [inline]\n sock_close+0x68/0x150 net/socket.c:1421\n __fput+0x2c1/0x660 fs/file_table.c:422\n __fput_sync+0x44/0x60 fs/file_table.c:507\n __do_sys_close fs/open.c:1556 [inline]\n __se_sys_close+0x101/0x1b0 fs/open.c:1541\n __x64_sys_close+0x1f/0x30 fs/open.c:1541\n do_syscall_64+0xd3/0x1d0\n entry_SYSCALL_64_after_hwframe+0x6d/0x75\n\nread to 0xffff88814b3278b8 of 8 bytes by task 10713 on cpu 0:\n sk_psock_data_ready include/linux/skmsg.h:464 [inline]\n sk_psock_skb_ingress_enqueue+0x32d/0x390 net/core/skmsg.c:555\n sk_psock_skb_ingress_self+0x185/0x1e0 net/core/skmsg.c:606\n sk_psock_verdict_apply net/core/skmsg.c:1008 [inline]\n sk_psock_verdict_recv+0x3e4/0x4a0 net/core/skmsg.c:1202\n unix_read_skb net/unix/af_unix.c:2546 [inline]\n unix_stream_read_skb+0x9e/0xf0 net/unix/af_unix.c:2682\n sk_psock_verdict_data_ready+0x77/0x220 net/core/skmsg.c:1223\n unix_stream_sendmsg+0x527/0x860 net/unix/af_unix.c:2339\n sock_sendmsg_nosec net/socket.c:730 [inline]\n __sock_sendmsg+0x140/0x180 net/socket.c:745\n ____sys_sendmsg+0x312/0x410 net/socket.c:2584\n ___sys_sendmsg net/socket.c:2638 [inline]\n __sys_sendmsg+0x1e9/0x280 net/socket.c:2667\n __do_sys_sendmsg net/socket.c:2676 [inline]\n __se_sys_sendmsg net/socket.c:2674 [inline]\n __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674\n do_syscall_64+0xd3/0x1d0\n entry_SYSCALL_64_after_hwframe+0x6d/0x75\n\nvalue changed: 0xffffffff83d7feb0 -> 0x0000000000000000\n\nReported by Kernel Concurrency Sanitizer on:\nCPU: 0 PID: 10713 Comm: syz-executor.4 Tainted: G W 6.8.0-syzkaller-08951-gfe46a7dd189e #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024\n\nPrior to this, commit 4cd12c6065df (\"bpf, sockmap: Fix NULL pointer\ndereference in sk_psock_verdict_data_ready()\") fixed one NULL pointer\nsimilarly due to no protection of saved_data_ready. Here is another\ndifferent caller causing the same issue because of the same reason. So\nwe should protect it with sk_callback_lock read lock because the writer\nside in the sk_psock_drop() uses \"write_lock_bh(&sk->sk_callback_lock);\".\n\nTo avoid errors that could happen in future, I move those two pairs of\nlock into the sk_psock_data_ready(), which is suggested by John Fastabend."
