possible deadlock in sk_diag_fill (2)

From: syzbot
Date: Mon May 11 2020 - 14:21:27 EST

Next message: syzbot: "memory leak in erase_aeb (2)"
Previous message: syzbot: "KASAN: slab-out-of-bounds Read in fl6_update_dst"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following crash on:

HEAD commit: e99332e7 gcc-10: mark more functions __init to avoid secti..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1557910c100000
kernel config: https://syzkaller.appspot.com/x/.config?x=8a96cf498e199d8b
dashboard link: https://syzkaller.appspot.com/bug?extid=c07a7e4d97298524f320
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c07a7e4d97298524f320@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
5.7.0-rc4-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/31514 is trying to acquire lock:
ffff88806be19668 (&u->lock/1){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:86 [inline]
ffff88806be19668 (&u->lock/1){+.+.}-{2:2}, at: sk_diag_fill.isra.0+0x9d0/0x10e0 net/unix/diag.c:154

but task is already holding lock:
ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:68 [inline]
ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_fill.isra.0+0x8eb/0x10e0 net/unix/diag.c:154

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (rlock-AF_UNIX){+.+.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159
skb_queue_tail+0x27/0x180 net/core/skbuff.c:3143
unix_dgram_sendmsg+0xc96/0x12e0 net/unix/af_unix.c:1806
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x308/0x7e0 net/socket.c:2362
___sys_sendmsg+0x100/0x170 net/socket.c:2416
__sys_sendmmsg+0x296/0x480 net/socket.c:2499
__compat_sys_sendmmsg net/compat.c:672 [inline]
__do_compat_sys_sendmmsg net/compat.c:679 [inline]
__se_compat_sys_sendmmsg net/compat.c:676 [inline]
__ia32_compat_sys_sendmmsg+0x9b/0x100 net/compat.c:676
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

-> #0 (&u->lock/1){+.+.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:2515 [inline]
check_prevs_add kernel/locking/lockdep.c:2620 [inline]
validate_chain kernel/locking/lockdep.c:3237 [inline]
__lock_acquire+0x2ab1/0x4c50 kernel/locking/lockdep.c:4355
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4934
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
sk_diag_dump_icons net/unix/diag.c:86 [inline]
sk_diag_fill.isra.0+0x9d0/0x10e0 net/unix/diag.c:154
sk_diag_dump net/unix/diag.c:192 [inline]
unix_diag_dump+0x441/0x550 net/unix/diag.c:220
netlink_dump+0x50b/0xf50 net/netlink/af_netlink.c:2245
__netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
netlink_dump_start include/linux/netlink.h:246 [inline]
unix_diag_handler_dump+0x3ea/0x7b0 net/unix/diag.c:321
__sock_diag_cmd net/core/sock_diag.c:233 [inline]
sock_diag_rcv_msg+0x2fe/0x3e0 net/core/sock_diag.c:264
netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:275
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
sock_write_iter+0x289/0x3c0 net/socket.c:1004
call_write_iter include/linux/fs.h:1907 [inline]
do_iter_readv_writev+0x5a8/0x850 fs/read_write.c:694
do_iter_write fs/read_write.c:999 [inline]
do_iter_write+0x18b/0x600 fs/read_write.c:980
compat_writev+0x1f1/0x390 fs/read_write.c:1352
do_compat_writev+0xd5/0x1d0 fs/read_write.c:1373
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(rlock-AF_UNIX);
lock(&u->lock/1);
lock(rlock-AF_UNIX);
lock(&u->lock/1);

*** DEADLOCK ***

5 locks held by syz-executor.3/31514:
#0: ffffffff8a58a388 (sock_diag_mutex){+.+.}-{3:3}, at: sock_diag_rcv+0x17/0x40 net/core/sock_diag.c:274
#1: ffffffff8a58a448 (sock_diag_table_mutex){+.+.}-{3:3}, at: __sock_diag_cmd net/core/sock_diag.c:228 [inline]
#1: ffffffff8a58a448 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg+0x18d/0x3e0 net/core/sock_diag.c:264
#2: ffff888050ce1630 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{3:3}, at: netlink_dump+0xd4/0xf50 net/netlink/af_netlink.c:2200
#3: ffffffff8a65df18 (unix_table_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
#3: ffffffff8a65df18 (unix_table_lock){+.+.}-{2:2}, at: unix_diag_dump+0x10c/0x550 net/unix/diag.c:206
#4: ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
#4: ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_dump_icons net/unix/diag.c:68 [inline]
#4: ffff888091bbf1e0 (rlock-AF_UNIX){+.+.}-{2:2}, at: sk_diag_fill.isra.0+0x8eb/0x10e0 net/unix/diag.c:154

stack backtrace:
CPU: 0 PID: 31514 Comm: syz-executor.3 Not tainted 5.7.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1846
check_prev_add kernel/locking/lockdep.c:2515 [inline]
check_prevs_add kernel/locking/lockdep.c:2620 [inline]
validate_chain kernel/locking/lockdep.c:3237 [inline]
__lock_acquire+0x2ab1/0x4c50 kernel/locking/lockdep.c:4355
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4934
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
sk_diag_dump_icons net/unix/diag.c:86 [inline]
sk_diag_fill.isra.0+0x9d0/0x10e0 net/unix/diag.c:154
sk_diag_dump net/unix/diag.c:192 [inline]
unix_diag_dump+0x441/0x550 net/unix/diag.c:220
netlink_dump+0x50b/0xf50 net/netlink/af_netlink.c:2245
__netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
netlink_dump_start include/linux/netlink.h:246 [inline]
unix_diag_handler_dump+0x3ea/0x7b0 net/unix/diag.c:321
__sock_diag_cmd net/core/sock_diag.c:233 [inline]
sock_diag_rcv_msg+0x2fe/0x3e0 net/core/sock_diag.c:264
netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:275
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
sock_write_iter+0x289/0x3c0 net/socket.c:1004
call_write_iter include/linux/fs.h:1907 [inline]
do_iter_readv_writev+0x5a8/0x850 fs/read_write.c:694
do_iter_write fs/read_write.c:999 [inline]
do_iter_write+0x18b/0x600 fs/read_write.c:980
compat_writev+0x1f1/0x390 fs/read_write.c:1352
do_compat_writev+0xd5/0x1d0 fs/read_write.c:1373
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Next message: syzbot: "memory leak in erase_aeb (2)"
Previous message: syzbot: "KASAN: slab-out-of-bounds Read in fl6_update_dst"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]