panic: Most recently used by tty

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 5446f43e Pull in r360099 from upstream llvm trunk (by Eli ..
git tree: freebsd
console output: https://syzkaller.appspot.com/x/log.txt?x=10d7bf58a00000
dashboard link: https://syzkaller.appspot.com/bug?extid=c9b6206303bf47bac87e

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+c9b620...@syzkaller.appspotmail.com

panic: Most recently used by tty

cpuid = 0
time = 100
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame
0xfffffe0024ba8690
vpanic() at vpanic+0x1e0/frame 0xfffffe0024ba86f0
panic() at panic+0x43/frame 0xfffffe0024ba8750
mtrash_ctor() at mtrash_ctor+0xed/frame 0xfffffe0024ba8790
uma_zalloc_arg() at uma_zalloc_arg+0x1036/frame 0xfffffe0024ba8840
malloc() at malloc+0xe1/frame 0xfffffe0024ba88b0
tty_alloc_mutex() at tty_alloc_mutex+0x22c/frame 0xfffffe0024ba88e0
pts_alloc() at pts_alloc+0x179/frame 0xfffffe0024ba8930
sys_posix_openpt() at sys_posix_openpt+0x94/frame 0xfffffe0024ba8970
ia32_syscall() at ia32_syscall+0x452/frame 0xfffffe0024ba8ab0
int0x80_syscall_common() at int0x80_syscall_common+0x9c/frame 0xa
KDB: enter: panic
[ thread pid 2923 tid 100932 ]
Stopped at kdb_enter+0x6a: movq $0,kdb_why


---
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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 5446f43e Pull in r360099 from upstream llvm trunk (by Eli ..
git tree: freebsd

console output: https://syzkaller.appspot.com/x/log.txt?x=14574caca00000
dashboard link: https://syzkaller.appspot.com/bug?extid=c9b6206303bf47bac87e
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14f0cac8a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c9b620...@syzkaller.appspotmail.com

panic: Most recently used by tty

cpuid = 1
time = 1557320204

KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame

0xfffffe001fa7c690
vpanic() at vpanic+0x1e0/frame 0xfffffe001fa7c6f0
panic() at panic+0x43/frame 0xfffffe001fa7c750
mtrash_ctor() at mtrash_ctor+0xed/frame 0xfffffe001fa7c790
uma_zalloc_arg() at uma_zalloc_arg+0x1036/frame 0xfffffe001fa7c840
malloc() at malloc+0xe1/frame 0xfffffe001fa7c8b0
tty_alloc_mutex() at tty_alloc_mutex+0x22c/frame 0xfffffe001fa7c8e0
pts_alloc() at pts_alloc+0x179/frame 0xfffffe001fa7c930
sys_posix_openpt() at sys_posix_openpt+0x94/frame 0xfffffe001fa7c970
ia32_syscall() at ia32_syscall+0x452/frame 0xfffffe001fa7cab0

int0x80_syscall_common() at int0x80_syscall_common+0x9c/frame 0xa
KDB: enter: panic

[ thread pid 788 tid 100119 ]