fs: fix oob in do_handle_open

[PATCH next] fs: fix oob in do_handle_open

Posted by Edward Adam Davis 1 year, 10 months ago

[Syzbot reported]
BUG: KASAN: slab-out-of-bounds in instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
Write of size 48 at addr ffff88802b8cbc88 by task syz-executor333/5090

CPU: 0 PID: 5090 Comm: syz-executor333 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
 _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
 copy_from_user include/linux/uaccess.h:183 [inline]
 handle_to_path fs/fhandle.c:203 [inline]
 do_handle_open+0x204/0x660 fs/fhandle.c:226
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x72/0x7a
[Fix] 
When copying data to f_handle, the length of the copied data should not include
the length of "struct file_handle".

Reported-by: syzbot+4139435cb1b34cf759c2@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/fhandle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fhandle.c b/fs/fhandle.c
index 53ed54711cd2..8a7f86c2139a 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
 	*handle = f_handle;
 	if (copy_from_user(&handle->f_handle,
 			   &ufh->f_handle,
-			   struct_size(ufh, f_handle, f_handle.handle_bytes))) {
+			   f_handle.handle_bytes)) {
 		retval = -EFAULT;
 		goto out_handle;
 	}
-- 
2.43.0

Re: [PATCH next] fs: fix oob in do_handle_open

Posted by Jeff Layton 1 year, 10 months ago

On Wed, 2024-04-03 at 14:54 +0800, Edward Adam Davis wrote:
> [Syzbot reported]
> BUG: KASAN: slab-out-of-bounds in instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
> BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
> Write of size 48 at addr ffff88802b8cbc88 by task syz-executor333/5090
> 
> CPU: 0 PID: 5090 Comm: syz-executor333 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  print_address_description mm/kasan/report.c:377 [inline]
>  print_report+0x169/0x550 mm/kasan/report.c:488
>  kasan_report+0x143/0x180 mm/kasan/report.c:601
>  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
>  instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
>  _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
>  copy_from_user include/linux/uaccess.h:183 [inline]
>  handle_to_path fs/fhandle.c:203 [inline]
>  do_handle_open+0x204/0x660 fs/fhandle.c:226
>  do_syscall_64+0xfb/0x240
>  entry_SYSCALL_64_after_hwframe+0x72/0x7a
> [Fix] 
> When copying data to f_handle, the length of the copied data should not include
> the length of "struct file_handle".
> 
> Reported-by: syzbot+4139435cb1b34cf759c2@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  fs/fhandle.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/fhandle.c b/fs/fhandle.c
> index 53ed54711cd2..8a7f86c2139a 100644
> --- a/fs/fhandle.c
> +++ b/fs/fhandle.c
> @@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
>  	*handle = f_handle;
>  	if (copy_from_user(&handle->f_handle,
>  			   &ufh->f_handle,
> -			   struct_size(ufh, f_handle, f_handle.handle_bytes))) {
> +			   f_handle.handle_bytes)) {
>  		retval = -EFAULT;
>  		goto out_handle;
>  	}

cc'ing Gustavo, since it looks like his patch in -next is what broke
this.

-- 
Jeff Layton <jlayton@kernel.org>

Re: [PATCH next] fs: fix oob in do_handle_open

Posted by Gustavo A. R. Silva 1 year, 10 months ago


On 03/04/24 02:48, Jeff Layton wrote:
> On Wed, 2024-04-03 at 14:54 +0800, Edward Adam Davis wrote:
>> [Syzbot reported]
>> BUG: KASAN: slab-out-of-bounds in instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
>> BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
>> Write of size 48 at addr ffff88802b8cbc88 by task syz-executor333/5090
>>
>> CPU: 0 PID: 5090 Comm: syz-executor333 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
>> Call Trace:
>>   <TASK>
>>   __dump_stack lib/dump_stack.c:88 [inline]
>>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>>   print_address_description mm/kasan/report.c:377 [inline]
>>   print_report+0x169/0x550 mm/kasan/report.c:488
>>   kasan_report+0x143/0x180 mm/kasan/report.c:601
>>   kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
>>   instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
>>   _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
>>   copy_from_user include/linux/uaccess.h:183 [inline]
>>   handle_to_path fs/fhandle.c:203 [inline]
>>   do_handle_open+0x204/0x660 fs/fhandle.c:226
>>   do_syscall_64+0xfb/0x240
>>   entry_SYSCALL_64_after_hwframe+0x72/0x7a
>> [Fix]
>> When copying data to f_handle, the length of the copied data should not include
>> the length of "struct file_handle".
>>
>> Reported-by: syzbot+4139435cb1b34cf759c2@syzkaller.appspotmail.com
>> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
>> ---
>>   fs/fhandle.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/fhandle.c b/fs/fhandle.c
>> index 53ed54711cd2..8a7f86c2139a 100644
>> --- a/fs/fhandle.c
>> +++ b/fs/fhandle.c
>> @@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
>>   	*handle = f_handle;
>>   	if (copy_from_user(&handle->f_handle,
>>   			   &ufh->f_handle,
>> -			   struct_size(ufh, f_handle, f_handle.handle_bytes))) {
>> +			   f_handle.handle_bytes)) {
>>   		retval = -EFAULT;
>>   		goto out_handle;
>>   	}
> 
> cc'ing Gustavo, since it looks like his patch in -next is what broke
> this.
> 

Oh, sorry about that folks. That looks pretty much like a copy/paste error.

The fix is correct.

Thanks, Edward!
--
Gustavo

Re: [PATCH next] fs: fix oob in do_handle_open

Posted by Christian Brauner 1 year, 10 months ago

On Wed, Apr 03, 2024 at 04:48:17AM -0400, Jeff Layton wrote:
> On Wed, 2024-04-03 at 14:54 +0800, Edward Adam Davis wrote:
> > [Syzbot reported]
> > BUG: KASAN: slab-out-of-bounds in instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
> > BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
> > Write of size 48 at addr ffff88802b8cbc88 by task syz-executor333/5090
> > 
> > CPU: 0 PID: 5090 Comm: syz-executor333 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> > Call Trace:
> >  <TASK>
> >  __dump_stack lib/dump_stack.c:88 [inline]
> >  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
> >  print_address_description mm/kasan/report.c:377 [inline]
> >  print_report+0x169/0x550 mm/kasan/report.c:488
> >  kasan_report+0x143/0x180 mm/kasan/report.c:601
> >  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
> >  instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
> >  _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
> >  copy_from_user include/linux/uaccess.h:183 [inline]
> >  handle_to_path fs/fhandle.c:203 [inline]
> >  do_handle_open+0x204/0x660 fs/fhandle.c:226
> >  do_syscall_64+0xfb/0x240
> >  entry_SYSCALL_64_after_hwframe+0x72/0x7a
> > [Fix] 
> > When copying data to f_handle, the length of the copied data should not include
> > the length of "struct file_handle".
> > 
> > Reported-by: syzbot+4139435cb1b34cf759c2@syzkaller.appspotmail.com
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> >  fs/fhandle.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/fhandle.c b/fs/fhandle.c
> > index 53ed54711cd2..8a7f86c2139a 100644
> > --- a/fs/fhandle.c
> > +++ b/fs/fhandle.c
> > @@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
> >  	*handle = f_handle;
> >  	if (copy_from_user(&handle->f_handle,
> >  			   &ufh->f_handle,
> > -			   struct_size(ufh, f_handle, f_handle.handle_bytes))) {
> > +			   f_handle.handle_bytes)) {
> >  		retval = -EFAULT;
> >  		goto out_handle;
> >  	}
> 
> cc'ing Gustavo, since it looks like his patch in -next is what broke
> this.

I'ved folded the fix into Gustavo's patch. Please see
https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs.misc&id=02426828cde24cd5b6cf5f30467cea085118f657