Description

In the Linux kernel, the following vulnerability has been resolved: netlink: annotate lockless accesses to nlk->max_recvmsg_len syzbot reported a data-race in data-race in netlink_recvmsg() [1] Indeed, netlink_recvmsg() can be run concurrently, and netlink_dump() also needs protection. [1] BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg read to 0xffff888141840b38 of 8 bytes by task 23057 on cpu 0: netlink_recvmsg+0xea/0x730 net/netlink/af_netlink.c:1988 sock_recvmsg_nosec net/socket.c:1017 [inline] sock_recvmsg net/socket.c:1038 [inline] __sys_recvfrom+0x1ee/0x2e0 net/socket.c:2194 __do_sys_recvfrom net/socket.c:2212 [inline] __se_sys_recvfrom net/socket.c:2208 [inline] __x64_sys_recvfrom+0x78/0x90 net/socket.c:2208 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd write to 0xffff888141840b38 of 8 bytes by task 23037 on cpu 1: netlink_recvmsg+0x114/0x730 net/netlink/af_netlink.c:1989 sock_recvmsg_nosec net/socket.c:1017 [inline] sock_recvmsg net/socket.c:1038 [inline] ____sys_recvmsg+0x156/0x310 net/socket.c:2720 ___sys_recvmsg net/socket.c:2762 [inline] do_recvmmsg+0x2e5/0x710 net/socket.c:2856 __sys_recvmmsg net/socket.c:2935 [inline] __do_sys_recvmmsg net/socket.c:2958 [inline] __se_sys_recvmmsg net/socket.c:2951 [inline] __x64_sys_recvmmsg+0xe2/0x160 net/socket.c:2951 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x0000000000000000 -> 0x0000000000001000 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 23037 Comm: syz-executor.2 Not tainted 6.3.0-rc4-syzkaller-00195-g5a57b48fdfcb #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023

References 5

• git.kernel.org https://git.kernel.org/stable/c/05c9e3fc93b02d18c3ab258d43350a6d44b40bbd
• git.kernel.org https://git.kernel.org/stable/c/7cff4103be7c402ecc3e7bf8f95a64089e3c91b8
• git.kernel.org https://git.kernel.org/stable/c/a1865f2e7d10dde00d35a2122b38d2e469ae67ed
• git.kernel.org https://git.kernel.org/stable/c/e3bcf2a77060bea4d8d09cb09d92c7056f07df5a
• git.kernel.org https://git.kernel.org/stable/c/fc4ba13013ddaea8b11b88fd52b35449e2d9cf85

Remediation