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Eric Dumazet authored
netlink_recvmsg() does not need to change transport header. If transport header was needed, it should have been reset by the producer (netlink_dump()), not the consumer(s). The following trace probably happened when multiple threads were using MSG_PEEK. BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg write to 0xffff88811e9f15b2 of 2 bytes by task 32012 on cpu 1: skb_reset_transport_header include/linux/skbuff.h:2760 [inline] netlink_recvmsg+0x1de/0x790 net/netlink/af_netlink.c:1978 sock_recvmsg_nosec net/socket.c:948 [inline] sock_recvmsg net/socket.c:966 [inline] __sys_recvfrom+0x204/0x2c0 net/socket.c:2097 __do_sys_recvfrom net/socket.c:2115 [inline] __se_sys_recvfrom net/socket.c:2111 [inline] __x64_sys_recvfrom+0x74/0x90 net/socket.c:2111 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae write to 0xffff88811e9f15b2 of 2 bytes by task 32005 on cpu 0: skb_reset_transport_header include/linux/skbuff.h:2760 [inline] netlink_recvmsg+0x1de/0x790 net/netlink/af_netlink.c:1978 ____sys_recvmsg+0x162/0x2f0 ___sys_recvmsg net/socket.c:2674 [inline] __sys_recvmsg+0x209/0x3f0 net/socket.c:2704 __do_sys_recvmsg net/socket.c:2714 [inline] __se_sys_recvmsg net/socket.c:2711 [inline] __x64_sys_recvmsg+0x42/0x50 net/socket.c:2711 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0xffff -> 0x0000 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 32005 Comm: syz-executor.4 Not tainted 5.18.0-rc1-syzkaller-00328-ge1f700eb-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 1da177e4 ("Linux-2.6.12-rc2") Signed-off-by:
Eric Dumazet <edumazet@google.com> Reported-by:
syzbot <syzkaller@googlegroups.com> Link: https://lore.kernel.org/r/20220505161946.2867638-1-eric.dumazet@gmail.comSigned-off-by:
Jakub Kicinski <kuba@kernel.org>
d5076fe4