UBUNTU-CVE-2024-26731

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UBUNTU-CVE-2024-26731

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready() syzbot reported the following NULL pointer dereference issue [1]: BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] RIP: 0010:0x0 [...] Call Trace: <TASK> sk_psock_verdict_data_ready+0x232/0x340 net/core/skmsg.c:1230 unix_stream_sendmsg+0x9b4/0x1230 net/unix/af_unix.c:2293 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 If sk_psock_verdict_data_ready() and sk_psock_stop_verdict() are called concurrently, psock->saved_data_ready can be NULL, causing the above issue. This patch fixes this issue by calling the appropriate data ready function using the sk_psock_data_ready() helper and protecting it from concurrency with sk->sk_callback_lock.

References: https://ubuntu.com/security/CVE-2024-26731, https://git.kernel.org/linus/4cd12c6065dfcdeba10f49949bffcf383b3952d8, https://git.kernel.org/stable/c/4588b13abcbd561ec67f5b3c1cb2eff690990a54, https://git.kernel.org/stable/c/9b099ed46dcaf1403c531ff02c3d7400fa37fa26, https://git.kernel.org/stable/c/d61608a4e394f23e0dca099df9eb8e555453d949, https://git.kernel.org/stable/c/4cd12c6065dfcdeba10f49949bffcf383b3952d8, https://www.cve.org/CVERecord?id=CVE-2024-26731