dihu wrote: > When user application calls read() with MSG_PEEK flag to read data > of bpf sockmap socket, kernel panic happens at > __tcp_bpf_recvmsg+0x12c/0x350. sk_msg is not removed from ingress_msg > queue after read out under MSG_PEEK flag is set. Because it's not > judged whether sk_msg is the last msg of ingress_msg queue, the next > sk_msg may be the head of ingress_msg queue, whose memory address of > sg page is invalid. So it's necessary to add check codes to prevent > this problem. > > [20759.125457] BUG: kernel NULL pointer dereference, address: > 0000000000000008 > [20759.132118] CPU: 53 PID: 51378 Comm: envoy Tainted: G E > 5.4.32 #1 > [20759.140890] Hardware name: Inspur SA5212M4/YZMB-00370-109, BIOS > 4.1.12 06/18/2017 > [20759.149734] RIP: 0010:copy_page_to_iter+0xad/0x300 > [20759.270877] __tcp_bpf_recvmsg+0x12c/0x350 > [20759.276099] tcp_bpf_recvmsg+0x113/0x370 > [20759.281137] inet_recvmsg+0x55/0xc0 > [20759.285734] __sys_recvfrom+0xc8/0x130 > [20759.290566] ? __audit_syscall_entry+0x103/0x130 > [20759.296227] ? syscall_trace_enter+0x1d2/0x2d0 > [20759.301700] ? __audit_syscall_exit+0x1e4/0x290 > [20759.307235] __x64_sys_recvfrom+0x24/0x30 > [20759.312226] do_syscall_64+0x55/0x1b0 > [20759.316852] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Signed-off-by: dihu <anny.hu@xxxxxxxxxxxxxxxxx> > --- > net/ipv4/tcp_bpf.c | 3 +++ > 1 file changed, 3 insertions(+) > Thanks, looks good to me. Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
