From: Cong Wang <xiyou.wangc...@gmail.com> Date: Tue, 7 Feb 2017 12:59:47 -0800
> Dmitry reported a kernel warning: > > WARNING: CPU: 3 PID: 2936 at net/kcm/kcmsock.c:627 > kcm_write_msgs+0x12e3/0x1b90 net/kcm/kcmsock.c:627 > CPU: 3 PID: 2936 Comm: a.out Not tainted 4.10.0-rc6+ #209 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:15 [inline] > dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 > panic+0x1fb/0x412 kernel/panic.c:179 > __warn+0x1c4/0x1e0 kernel/panic.c:539 > warn_slowpath_null+0x2c/0x40 kernel/panic.c:582 > kcm_write_msgs+0x12e3/0x1b90 net/kcm/kcmsock.c:627 > kcm_sendmsg+0x163a/0x2200 net/kcm/kcmsock.c:1029 > sock_sendmsg_nosec net/socket.c:635 [inline] > sock_sendmsg+0xca/0x110 net/socket.c:645 > sock_write_iter+0x326/0x600 net/socket.c:848 > new_sync_write fs/read_write.c:499 [inline] > __vfs_write+0x483/0x740 fs/read_write.c:512 > vfs_write+0x187/0x530 fs/read_write.c:560 > SYSC_write fs/read_write.c:607 [inline] > SyS_write+0xfb/0x230 fs/read_write.c:599 > entry_SYSCALL_64_fastpath+0x1f/0xc2 > > when calling syscall(__NR_write, sock2, 0x208aaf27ul, 0x0ul) on a KCM > seqpacket socket. It appears that kcm_sendmsg() does not handle len==0 > case correctly, which causes an empty skb is allocated and queued. > Fix this by skipping the skb allocation for len==0 case. > > Reported-by: Dmitry Vyukov <dvyu...@google.com> > Cc: Tom Herbert <t...@herbertland.com> > Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com> Applied and queued up for -stable.
