KASAN: out-of-bounds Read in unwind_next_frame (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3207316b Linux 4.19.164
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15d21c2b500000
kernel config: https://syzkaller.appspot.com/x/.config?x=ce6a43827932e236
dashboard link: https://syzkaller.appspot.com/bug?extid=acb4e54dcc8469f15cb5
compiler: gcc (GCC) 10.1.0-syz 20200507

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+acb4e5...@syzkaller.appspotmail.com

ldm_validate_privheads(): Disk read failed.
loop4: p2 < >
loop4: partition table partially beyond EOD, truncated
loop4: p2 size 2 extends beyond EOD, truncated
==================================================================
BUG: KASAN: out-of-bounds in user_mode arch/x86/include/asm/ptrace.h:131 [inline]
BUG: KASAN: out-of-bounds in unwind_next_frame+0x151a/0x1c60 arch/x86/kernel/unwind_orc.c:410
Read of size 8 at addr ffff888095277d40 by task syz-executor.5/26241

CPU: 0 PID: 26241 Comm: syz-executor.5 Not tainted 4.19.164-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+0x1fc/0x2fe lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
user_mode arch/x86/include/asm/ptrace.h:131 [inline]
unwind_next_frame+0x151a/0x1c60 arch/x86/kernel/unwind_orc.c:410
__save_stack_trace+0x9f/0x190 arch/x86/kernel/stacktrace.c:44
save_stack_trace_tsk+0x9c/0xf0 arch/x86/kernel/stacktrace.c:76
proc_pid_stack+0x202/0x350 fs/proc/base.c:456
proc_single_show+0xeb/0x170 fs/proc/base.c:755
seq_read+0x4be/0x1160 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:701 [inline]
do_loop_readv_writev fs/read_write.c:688 [inline]
do_iter_read+0x471/0x630 fs/read_write.c:925
vfs_readv+0xe5/0x150 fs/read_write.c:987
do_preadv fs/read_write.c:1071 [inline]
__do_sys_preadv fs/read_write.c:1121 [inline]
__se_sys_preadv fs/read_write.c:1116 [inline]
__x64_sys_preadv+0x22b/0x310 fs/read_write.c:1116
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45e219
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f70c31bbc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045e219
RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000004
RBP: 000000000119bfd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c
R13: 00007fff4ef5b53f R14: 00007f70c31bc9c0 R15: 000000000119bf8c

The buggy address belongs to the page:
page:ffffea0002549dc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea0002c16608 ffffea0002549d88 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888095277c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888095277c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888095277d00: f1 f1 f1 f1 00 00 f3 f3 00 00 00 00 00 00 00 00
^
ffff888095277d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888095277e00: 00 f1 f1 f1 f1 00 f2 f2 f2 00 f2 f2 f2 00 00 f3
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.