Re: [syzbot] BUG: sleeping function called from invalid context in _copy_to_iter
From: Shoaib Rao
Date: Mon Aug 09 2021 - 13:33:28 EST
This seems like a false positive. 1) The function will not sleep because
it only calls copy routine if the byte is present. 2). There is no
difference between this new call and the older calls in
unix_stream_read_generic().
Shoaib
On 8/8/21 4:38 PM, syzbot wrote:
Hello,
syzbot found the following issue on:
HEAD commit: c2eecaa193ff pktgen: Remove redundant clone_skb override
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12e3a69e300000
kernel config: https://syzkaller.appspot.com/x/.config?x=aba0c23f8230e048
dashboard link: https://syzkaller.appspot.com/bug?extid=8760ca6c1ee783ac4abd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15c5b104300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10062aaa300000
The issue was bisected to:
commit 314001f0bf927015e459c9d387d62a231fe93af3
Author: Rao Shoaib <rao.shoaib@xxxxxxxxxx>
Date: Sun Aug 1 07:57:07 2021 +0000
af_unix: Add OOB support
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10765f8e300000
final oops: https://syzkaller.appspot.com/x/report.txt?x=12765f8e300000
console output: https://syzkaller.appspot.com/x/log.txt?x=14765f8e300000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8760ca6c1ee783ac4abd@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 314001f0bf92 ("af_unix: Add OOB support")
BUG: sleeping function called from invalid context at lib/iov_iter.c:619
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 8443, name: syz-executor700
2 locks held by syz-executor700/8443:
#0: ffff888028fa0d00 (&u->iolock){+.+.}-{3:3}, at: unix_stream_read_generic+0x16c6/0x2190 net/unix/af_unix.c:2501
#1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline]
#1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: unix_stream_read_generic+0x16d0/0x2190 net/unix/af_unix.c:2502
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 8443 Comm: syz-executor700 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9154
__might_fault+0x6e/0x180 mm/memory.c:5258
_copy_to_iter+0x199/0x1600 lib/iov_iter.c:619
copy_to_iter include/linux/uio.h:139 [inline]
simple_copy_to_iter+0x4c/0x70 net/core/datagram.c:519
__skb_datagram_iter+0x10f/0x770 net/core/datagram.c:425
skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:533
skb_copy_datagram_msg include/linux/skbuff.h:3620 [inline]
unix_stream_read_actor+0x78/0xc0 net/unix/af_unix.c:2701
unix_stream_recv_urg net/unix/af_unix.c:2433 [inline]
unix_stream_read_generic+0x17cd/0x2190 net/unix/af_unix.c:2504
unix_stream_recvmsg+0xb1/0xf0 net/unix/af_unix.c:2717
sock_recvmsg_nosec net/socket.c:944 [inline]
sock_recvmsg net/socket.c:962 [inline]
sock_recvmsg net/socket.c:958 [inline]
____sys_recvmsg+0x2c4/0x600 net/socket.c:2622
___sys_recvmsg+0x127/0x200 net/socket.c:2664
do_recvmmsg+0x24d/0x6d0 net/socket.c:2758
__sys_recvmmsg net/socket.c:2837 [inline]
__do_sys_recvmmsg net/socket.c:2860 [inline]
__se_sys_recvmmsg net/socket.c:2853 [inline]
__x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2853
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43ef39
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffca8776d68 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ef39
RDX: 0000000000000700 RSI: 0000000020001140 RDI: 0000000000000004
RBP: 0000000000402f20 R08: 0000000000000000 R09: 0000000000400488
R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000402fb0
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488
=============================
[ BUG: Invalid wait context ]
5.14.0-rc3-syzkaller #0 Tainted: G W
-----------------------------
syz-executor700/8443 is trying to lock:
ffff8880212b6a28 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0xa3/0x180 mm/memory.c:5260
other info that might help us debug this:
context-{4:4}
2 locks held by syz-executor700/8443:
#0: ffff888028fa0d00 (&u->iolock){+.+.}-{3:3}, at: unix_stream_read_generic+0x16c6/0x2190 net/unix/af_unix.c:2501
#1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline]
#1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: unix_stream_read_generic+0x16d0/0x2190 net/unix/af_unix.c:2502
stack backtrace:
CPU: 1 PID: 8443 Comm: syz-executor700 Tainted: G W 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
print_lock_invalid_wait_context kernel/locking/lockdep.c:4666 [inline]
check_wait_context kernel/locking/lockdep.c:4727 [inline]
__lock_acquire.cold+0x213/0x3ab kernel/locking/lockdep.c:4965
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__might_fault mm/memory.c:5261 [inline]
__might_fault+0x106/0x180 mm/memory.c:5246
_copy_to_iter+0x199/0x1600 lib/iov_iter.c:619
copy_to_iter include/linux/uio.h:139 [inline]
simple_copy_to_iter+0x4c/0x70 net/core/datagram.c:519
__skb_datagram_iter+0x10f/0x770 net/core/datagram.c:425
skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:533
skb_copy_datagram_msg include/linux/skbuff.h:3620 [inline]
unix_stream_read_actor+0x78/0xc0 net/unix/af_unix.c:2701
unix_stream_recv_urg net/unix/af_unix.c:2433 [inline]
unix_stream_read_generic+0x17cd/0x2190 net/unix/af_unix.c:2504
unix_stream_recvmsg+0xb1/0xf0 net/unix/af_unix.c:2717
sock_recvmsg_nosec net/socket.c:944 [inline]
sock_recvmsg net/socket.c:962 [inline]
sock_recvmsg net/socket.c:958 [inline]
____sys_recvmsg+0x2c4/0x600 net/socket.c:2622
___sys_recvmsg+0x127/0x200 net/socket.c:2664
do_recvmmsg+0x24d/0x6d0 net/socket.c:2758
__sys_recvmmsg net/socket.c:2837 [inline]
__do_sys_recvmmsg net/socket.c:2860 [inline]
__se_sys_recvmmsg net/socket.c:2853 [inline]
__x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2853
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43ef39
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffca8776d68 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ef39
RDX: 0000000000000700 RSI: 0000000020001140 RDI: 0000000000000004
RBP: 0000000000402f20 R08: 0000000000000000 R09: 0000000000400488
R10: 0000000000000007 R11: 0000000000000246 R12: 0000
---
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