KASAN: stack-out-of-bounds Read in __free_filter

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
b284d4d5a6785f8cd07eda2646a95782373cd01e (Tue Apr 10 19:25:30 2018 +0000)
Merge tag 'ceph-for-4.17-rc1' of git://github.com/ceph/ceph-client
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=dadcc936587643d7f568

So far this crash happened 6 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6547381214511104
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=5485642750361600
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=5352489637380096
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-1223000601505858474
compiler: gcc (GCC) 8.0.1 20180301 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+dadcc9...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

RDX: 000000002099aff9 RSI: 0000000040082406 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 0000000000000001 R09: 00007ffe76420032
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: stack-out-of-bounds in __read_once_size
include/linux/compiler.h:188 [inline]
BUG: KASAN: stack-out-of-bounds in free_prog
kernel/trace/trace_events_filter.c:988 [inline]
BUG: KASAN: stack-out-of-bounds in __free_filter.part.6+0x1ac/0x1d0
kernel/trace/trace_events_filter.c:1012
Read of size 8 at addr ffff8801b2cd7698 by task syzkaller788882/4452

CPU: 0 PID: 4452 Comm: syzkaller788882 Not tainted 4.16.0+ #17
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
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0xac/0x2f5 mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
__read_once_size include/linux/compiler.h:188 [inline]
free_prog kernel/trace/trace_events_filter.c:988 [inline]
__free_filter.part.6+0x1ac/0x1d0 kernel/trace/trace_events_filter.c:1012
__free_filter kernel/trace/trace_events_filter.c:1009 [inline]
ftrace_profile_set_filter+0x159/0x2b0
kernel/trace/trace_events_filter.c:2053
perf_event_set_filter+0x248/0x1230 kernel/events/core.c:9064
_perf_ioctl+0x84c/0x1650 kernel/events/core.c:5056
perf_ioctl+0x59/0x80 kernel/events/core.c:5107
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1cf/0x1650 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
SYSC_ioctl fs/ioctl.c:708 [inline]
SyS_ioctl+0x24/0x30 fs/ioctl.c:706
do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x440519
RSP: 002b:00007ffe7642b3a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440519
RDX: 000000002099aff9 RSI: 0000000040082406 RDI: 0000000000000003
RBP: 00000000006cb018 R08: 0000000000000001 R09: 00007ffe76420032
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006cb35c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea0006cb0101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801b2cd7580: 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2 f3
ffff8801b2cd7600: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 f1 f1 f1
> ffff8801b2cd7680: f1 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00
^
ffff8801b2cd7700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
ffff8801b2cd7780: f1 f1 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
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[Steven Rostedt]

On Wed, 11 Apr 2018 05:02:02 -0700
syzbot <syzbot+dadcc9...@syzkaller.appspotmail.com> wrote:

> Hello,
>
> syzbot hit the following crash on upstream commit
> b284d4d5a6785f8cd07eda2646a95782373cd01e (Tue Apr 10 19:25:30 2018 +0000)
> Merge tag 'ceph-for-4.17-rc1' of git://github.com/ceph/ceph-client
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=dadcc936587643d7f568
>
> So far this crash happened 6 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6547381214511104
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=5485642750361600
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=5352489637380096
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-1223000601505858474
> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+dadcc9...@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
>

Can you try this patch?

-- Steve

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 33b7720e2aa1..5c07ae2ac5d7 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1705,18 +1705,16 @@ static int create_filter(struct trace_event_call *call,
struct event_filter **filterp)
{
struct filter_parse_error *pe = NULL;
- struct event_filter *filter = NULL;
int err;

- err = create_filter_start(filter_string, set_str, &pe, &filter);
+ err = create_filter_start(filter_string, set_str, &pe, filterp);
if (err)
return err;

- err = process_preds(call, filter_string, filter, pe);
+ err = process_preds(call, filter_string, *filterp, pe);
if (err && set_str)
- append_filter_err(pe, filter);
+ append_filter_err(pe, *filterp);

- *filterp = filter;
return err;
}

@@ -1740,24 +1738,22 @@ static int create_system_filter(struct trace_subsystem_dir *dir,
struct trace_array *tr,
char *filter_str, struct event_filter **filterp)
{
- struct event_filter *filter = NULL;
struct filter_parse_error *pe = NULL;
int err;

- err = create_filter_start(filter_str, true, &pe, &filter);
+ err = create_filter_start(filter_str, true, &pe, filterp);
if (!err) {
err = process_system_preds(dir, tr, pe, filter_str);
if (!err) {
/* System filters just show a default message */
- kfree(filter->filter_string);
- filter->filter_string = NULL;
+ kfree((*filterp)->filter_string);
+ (*filterp)->filter_string = NULL;
} else {
- append_filter_err(pe, filter);
+ append_filter_err(pe, *filterp);
}
}
create_filter_finish(pe);

- *filterp = filter;
return err;
}

@@ -1765,7 +1761,7 @@ static int create_system_filter(struct trace_subsystem_dir *dir,
int apply_event_filter(struct trace_event_file *file, char *filter_string)
{
struct trace_event_call *call = file->event_call;
- struct event_filter *filter;
+ struct event_filter *filter = NULL;
int err;

if (!strcmp(strstrip(filter_string), "0")) {
@@ -1818,7 +1814,7 @@ int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
{
struct event_subsystem *system = dir->subsystem;
struct trace_array *tr = dir->tr;
- struct event_filter *filter;
+ struct event_filter *filter = NULL;
int err = 0;

mutex_lock(&event_mutex);
@@ -2025,7 +2021,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id,
char *filter_str)
{
int err;
- struct event_filter *filter;
+ struct event_filter *filter = NULL;
struct trace_event_call *call;

mutex_lock(&event_mutex);

[Dmitry Vyukov]

On Wed, Apr 11, 2018 at 4:47 PM, Steven Rostedt <ros...@goodmis.org> wrote:
> On Wed, 11 Apr 2018 05:02:02 -0700
> syzbot <syzbot+dadcc9...@syzkaller.appspotmail.com> wrote:
>
>> Hello,
>>
>> syzbot hit the following crash on upstream commit
>> b284d4d5a6785f8cd07eda2646a95782373cd01e (Tue Apr 10 19:25:30 2018 +0000)
>> Merge tag 'ceph-for-4.17-rc1' of git://github.com/ceph/ceph-client
>> syzbot dashboard link:
>> https://syzkaller.appspot.com/bug?extid=dadcc936587643d7f568
>>
>> So far this crash happened 6 times on upstream.
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6547381214511104
>> syzkaller reproducer:
>> https://syzkaller.appspot.com/x/repro.syz?id=5485642750361600
>> Raw console output:
>> https://syzkaller.appspot.com/x/log.txt?id=5352489637380096
>> Kernel config:
>> https://syzkaller.appspot.com/x/.config?id=-1223000601505858474
>> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+dadcc9...@syzkaller.appspotmail.com
>> It will help syzbot understand when the bug is fixed. See footer for
>> details.
>> If you forward the report, please keep this part and the footer.
>>
>
> Can you try this patch?

Hi Steve,

Instructions for asking syzbot to test a patch are here:

https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot

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[Steven Rostedt]

On Wed, 11 Apr 2018 16:51:02 +0200
Dmitry Vyukov <dvy...@google.com> wrote:

> Hi Steve,
>
> Instructions for asking syzbot to test a patch are here:
>
> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot

I'll just add reported-by and add the patch. It does fix a bug,
regardless. I have other things I need to work on to spend any more
time on this one.

-- Steve

[Dmitry Vyukov]

This will work too.

Thanks for the quick fix!