WARNING in arch_uprobe_analyze_insn

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    66e1c94db3cd Merge branch 'x86-pti-for-linus' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11817107800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fcce42b221691ff9
dashboard link: https://syzkaller.appspot.com/bug?extid=30d675e3ca03c1c351e7
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=143d5417800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11178e97800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+30d675e3ca03c1c351e7@xxxxxxxxxxxxxxxxxxxxxxxxx

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296 insn_complete  
arch/x86/include/asm/insn.h:147 [inline]
WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296 uprobe_init_insn  
arch/x86/kernel/uprobes.c:296 [inline]
WARNING: CPU: 0 PID: 4511 at arch/x86/kernel/uprobes.c:296  
arch_uprobe_analyze_insn+0x13d/0x15f0 arch/x86/kernel/uprobes.c:861
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4511 Comm: syz-executor347 Not tainted 4.17.0-rc4+ #46
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+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:insn_complete arch/x86/include/asm/insn.h:147 [inline]
RIP: 0010:uprobe_init_insn arch/x86/kernel/uprobes.c:296 [inline]
RIP: 0010:arch_uprobe_analyze_insn+0x13d/0x15f0  
arch/x86/kernel/uprobes.c:861
RSP: 0018:ffff8801cf277510 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801cf277560 RCX: ffffffff876ccf2a
RDX: 0000000000000004 RSI: ffffffff876ce6ab RDI: ffff8801cf27759c
RBP: ffff8801cf277628 R08: ffff8801d8c0a5c0 R09: ffff8801cf277560
R10: ffff8801d7ad81d0 R11: ffff8801cf2775af R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8801d7ad8080 R15: ffff8801cf277600
 prepare_uprobe kernel/events/uprobes.c:610 [inline]
 install_breakpoint.isra.21+0x710/0x830 kernel/events/uprobes.c:657
 uprobe_mmap+0x6a0/0xcf0 kernel/events/uprobes.c:1089
 mmap_region+0x5c8/0x1870 mm/mmap.c:1807
 do_mmap+0xde2/0x1360 mm/mmap.c:1535
 do_mmap_pgoff include/linux/mm.h:2237 [inline]
 vm_mmap_pgoff+0x1fb/0x2a0 mm/util.c:357
 ksys_mmap_pgoff+0x4c9/0x640 mm/mmap.c:1585
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43ff29
RSP: 002b:00007ffc922a4898 EFLAGS: 00000212 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ff29
RDX: 0000000000000000 RSI: 0000000000002000 RDI: 000000002000c000
RBP: 00000000006ca018 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000012 R11: 0000000000000212 R12: 0000000000401850
R13: 00000000004018e0 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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