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

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+dadcc936587643d7f568@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.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

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

[Steven Rostedt]

On Wed, 11 Apr 2018 05:02:02 -0700
syzbot <syzbot+dadcc936587643d7f568@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+dadcc936587643d7f568@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);

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

[Dmitry Vyukov]

On Wed, Apr 11, 2018 at 4:47 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 11 Apr 2018 05:02:02 -0700
> syzbot <syzbot+dadcc936587643d7f568@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+dadcc936587643d7f568@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

> -- 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);
>
> --
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Re: KASAN: stack-out-of-bounds Read in __free_filter

[Steven Rostedt]

On Wed, 11 Apr 2018 16:51:02 +0200
Dmitry Vyukov <dvyukov@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

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

[Dmitry Vyukov]

On Wed, Apr 11, 2018 at 4:58 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 11 Apr 2018 16:51:02 +0200
> Dmitry Vyukov <dvyukov@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.


This will work too.

Thanks for the quick fix!