KASAN: out-of-bounds Read in unwind_next_frame

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 856452b4 ANDROID: uid_sys_stats: Copy task_struct comm fie..
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=135f44f8400000
kernel config: https://syzkaller.appspot.com/x/.config?x=5f994bbdedef826
dashboard link: https://syzkaller.appspot.com/bug?extid=09f6c15a17c88639711c
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16b61f44400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c114d2400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+09f6c1...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in unwind_next_frame+0xcd/0xe0
arch/x86/kernel/unwind_frame.c:51
Read of size 8 at addr ffff8801cb67f8b0 by task syz-executor900/21578

CPU: 0 PID: 21578 Comm: syz-executor900 Not tainted 4.9.118-g856452b #73
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
ffff8801cb7277b8 ffffffff81eb4b89 ffffea00072d9fc0 ffff8801cb67f8b0
0000000000000000 ffff8801cb67f8b8 ffff8801caead3c0 ffff8801cb7277f0
ffffffff81567f29 ffff8801cb67f8b0 0000000000000008 0000000000000000
Call Trace:
[<ffffffff81eb4b89>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffffff81eb4b89>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
[<ffffffff81567f29>] print_address_description+0x6c/0x234
mm/kasan/report.c:256
[<ffffffff81568333>] kasan_report_error mm/kasan/report.c:355 [inline]
[<ffffffff81568333>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
[<ffffffff8153beb4>] __asan_report_load8_noabort+0x14/0x20
mm/kasan/report.c:433
[<ffffffff810d2ead>] unwind_next_frame+0xcd/0xe0
arch/x86/kernel/unwind_frame.c:51
[<ffffffff8107b9cd>] __save_stack_trace+0x7d/0xf0
arch/x86/kernel/stacktrace.c:42
[<ffffffff8107baa8>] save_stack_trace_tsk+0x48/0x70
arch/x86/kernel/stacktrace.c:71
[<ffffffff816d7dc8>] proc_pid_stack+0x148/0x220 fs/proc/base.c:469
[<ffffffff816d94bd>] proc_single_show+0xfd/0x170 fs/proc/base.c:771
[<ffffffff815ed7b6>] seq_read+0x4b6/0x12e0 fs/seq_file.c:240
[<ffffffff8156f7b5>] do_loop_readv_writev.part.18+0xd5/0x280
fs/read_write.c:718
[<ffffffff81573705>] do_loop_readv_writev fs/read_write.c:707 [inline]
[<ffffffff81573705>] do_readv_writev+0x565/0x7a0 fs/read_write.c:873
[<ffffffff815739c4>] vfs_readv+0x84/0xc0 fs/read_write.c:897
[<ffffffff81573df7>] do_preadv+0x197/0x240 fs/read_write.c:974
[<ffffffff815773b0>] SYSC_preadv fs/read_write.c:1024 [inline]
[<ffffffff815773b0>] SyS_preadv+0x30/0x40 fs/read_write.c:1019
[<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
[<ffffffff839fca93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00072d9fc0 count:0 mapcount:0 mapping: (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801cb67f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801cb67f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff8801cb67f880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^
ffff8801cb67f900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801cb67f980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 6d46bcc5 ANDROID: x86_64_cuttlefish_defconfig: disable CON..
git tree: android-4.14
console output: https://syzkaller.appspot.com/x/log.txt?x=14b4bbe6400000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d42c81ed97e27e5
dashboard link: https://syzkaller.appspot.com/bug?extid=3a7b2a527f88ef40e5e1

compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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+3a7b2a...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in deref_stack_regs
arch/x86/kernel/unwind_orc.c:290 [inline]
BUG: KASAN: out-of-bounds in unwind_next_frame+0x1595/0x1930
arch/x86/kernel/unwind_orc.c:420
Read of size 8 at addr ffff88019df4f818 by task syz-executor1/25085

CPU: 1 PID: 25085 Comm: syz-executor1 Not tainted 4.14.76+ #20
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0xb9/0x11b lib/dump_stack.c:53
print_address_description+0x60/0x22b mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
deref_stack_regs arch/x86/kernel/unwind_orc.c:290 [inline]
unwind_next_frame+0x1595/0x1930 arch/x86/kernel/unwind_orc.c:420
__save_stack_trace+0x7d/0xf0 arch/x86/kernel/stacktrace.c:44
save_stack_trace_tsk+0x3e/0x60 arch/x86/kernel/stacktrace.c:73
proc_pid_stack+0x17c/0x260 fs/proc/base.c:460
proc_single_show+0xf1/0x160 fs/proc/base.c:762
seq_read+0x4e0/0x11d0 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:698 [inline]
do_iter_read+0x3cc/0x580 fs/read_write.c:922
vfs_readv+0xe6/0x150 fs/read_write.c:984
do_preadv+0x187/0x230 fs/read_write.c:1068
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007fae9f29dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457569
RDX: 1000000000000156 RSI: 0000000020000480 RDI: 0000000000000006
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fae9f29e6d4
R13: 00000000004c3088 R14: 00000000004d4a40 R15: 00000000ffffffff

The buggy address belongs to the page:

page:ffffea000677d3c0 count:0 mapcount:0 mapping: (null) index:0x0
flags: 0x4000000000000000()
raw: 4000000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea000677d3e0 0000000000000000 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88019df4f700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88019df4f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff88019df4f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^
ffff88019df4f880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88019df4f900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

[syzbot]

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