uvm_fault: rw_enter (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5dea098c4cfa fix a char signedness bug such that this test..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=1711fcd0980000
kernel config: https://syzkaller.appspot.com/x/.config?x=7058272de1526588
dashboard link: https://syzkaller.appspot.com/bug?extid=fc51d6417fbd1e56a7ee

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c17cfcd4dc3e/disk-5dea098c.raw.xz
bsd.gdb: https://storage.googleapis.com/syzbot-assets/30dd4cf7d821/bsd-5dea098c.gdb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f6dd2311320/kernel-5dea098c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fc51d6...@syzkaller.appspotmail.com

uvm_fault(0xfffffd807eff3528, 0x0, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at rw_enter+0x172: movq 0(%rax),%r15
TID PID UID PRFLAGS PFLAGS CPU COMMAND
*405385 54563 0 0x1a000002 0x4000000 0K syz-fuzzer
161904 35677 0 0x14000 0x200 1 softnet0
rw_enter(0,1) at rw_enter+0x172 sys/kern/kern_rwlock.c:253
uvm_vnp_uncache(fffffd80740cd3b8) at uvm_vnp_uncache+0x3f sys/uvm/uvm_vnode.c:1373
dounlinkat(ffff80002a148f68,ffffff9c,c000599680,0) at dounlinkat+0xf6 sys/kern/vfs_syscalls.c:1891
syscall(ffff80002a1f23e0) at syscall+0x854 mi_syscall sys/sys/syscall_mi.h:180 [inline]
syscall(ffff80002a1f23e0) at syscall+0x854 sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x2725ff1e0, count: 10
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports. Insufficient info makes it difficult to find and fix bugs.


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