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* KASAN: use-after-free Read in xlog_alloc_log (2)
@ 2019-11-30  7:19 syzbot
  2019-12-03 13:48 ` Brian Foster
  0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2019-11-30  7:19 UTC (permalink / raw)
  To: darrick.wong, linux-kernel, linux-xfs, syzkaller-bugs

Hello,

syzbot found the following crash on:

HEAD commit:    81b6b964 Merge branch 'master' of git://git.kernel.org/pub..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13b27696e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=773597fe8d7cb41a
dashboard link: https://syzkaller.appspot.com/bug?extid=c732f8644185de340492
compiler:       gcc (GCC) 9.0.0 20181231 (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+c732f8644185de340492@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in xlog_alloc_log+0x1398/0x14b0  
fs/xfs/xfs_log.c:1495
Read of size 8 at addr ffff888068139890 by task syz-executor.3/32544

CPU: 0 PID: 32544 Comm: syz-executor.3 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118
  print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
  __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
  kasan_report+0x12/0x20 mm/kasan/common.c:634
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
  xlog_alloc_log+0x1398/0x14b0 fs/xfs/xfs_log.c:1495
  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
  mount_bdev+0x304/0x3c0 fs/super.c:1415
  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
  vfs_get_tree+0x8e/0x300 fs/super.c:1545
  do_new_mount fs/namespace.c:2822 [inline]
  do_mount+0x135a/0x1b50 fs/namespace.c:3142
  ksys_mount+0xdb/0x150 fs/namespace.c:3351
  __do_sys_mount fs/namespace.c:3365 [inline]
  __se_sys_mount fs/namespace.c:3362 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45d0ca
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 4d 8c fb ff c3 66 2e 0f  
1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 2a 8c fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f525b430a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f525b430b40 RCX: 000000000045d0ca
RDX: 00007f525b430ae0 RSI: 0000000020000100 RDI: 00007f525b430b00
RBP: 0000000000000001 R08: 00007f525b430b40 R09: 00007f525b430ae0
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004
R13: 00000000004ca258 R14: 00000000004e2870 R15: 00000000ffffffff

Allocated by task 32544:
  save_stack+0x23/0x90 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  __kasan_kmalloc mm/kasan/common.c:510 [inline]
  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
  kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
  __do_kmalloc mm/slab.c:3655 [inline]
  __kmalloc+0x163/0x770 mm/slab.c:3664
  kmalloc include/linux/slab.h:561 [inline]
  kmem_alloc+0x15b/0x4d0 fs/xfs/kmem.c:21
  kmem_zalloc fs/xfs/kmem.h:68 [inline]
  xlog_alloc_log+0xcce/0x14b0 fs/xfs/xfs_log.c:1437
  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
  mount_bdev+0x304/0x3c0 fs/super.c:1415
  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
  vfs_get_tree+0x8e/0x300 fs/super.c:1545
  do_new_mount fs/namespace.c:2822 [inline]
  do_mount+0x135a/0x1b50 fs/namespace.c:3142
  ksys_mount+0xdb/0x150 fs/namespace.c:3351
  __do_sys_mount fs/namespace.c:3365 [inline]
  __se_sys_mount fs/namespace.c:3362 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 32544:
  save_stack+0x23/0x90 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  kasan_set_free_info mm/kasan/common.c:332 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
  __cache_free mm/slab.c:3425 [inline]
  kfree+0x10a/0x2c0 mm/slab.c:3756
  kvfree+0x61/0x70 mm/util.c:593
  kmem_free fs/xfs/kmem.h:61 [inline]
  xlog_alloc_log+0xeb5/0x14b0 fs/xfs/xfs_log.c:1497
  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
  mount_bdev+0x304/0x3c0 fs/super.c:1415
  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
  vfs_get_tree+0x8e/0x300 fs/super.c:1545
  do_new_mount fs/namespace.c:2822 [inline]
  do_mount+0x135a/0x1b50 fs/namespace.c:3142
  ksys_mount+0xdb/0x150 fs/namespace.c:3351
  __do_sys_mount fs/namespace.c:3365 [inline]
  __se_sys_mount fs/namespace.c:3362 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888068139800
  which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 144 bytes inside of
  1024-byte region [ffff888068139800, ffff888068139c00)
The buggy address belongs to the page:
page:ffffea0001a04e40 refcount:1 mapcount:0 mapping:ffff8880aa400c40  
index:0x0
raw: 00fffe0000000200 ffffea0002728148 ffffea00015604c8 ffff8880aa400c40
raw: 0000000000000000 ffff888068139000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff888068139780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff888068139800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888068139880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                          ^
  ffff888068139900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888068139980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: KASAN: use-after-free Read in xlog_alloc_log (2)
  2019-11-30  7:19 KASAN: use-after-free Read in xlog_alloc_log (2) syzbot
@ 2019-12-03 13:48 ` Brian Foster
  0 siblings, 0 replies; 3+ messages in thread
From: Brian Foster @ 2019-12-03 13:48 UTC (permalink / raw)
  To: syzbot; +Cc: darrick.wong, linux-kernel, linux-xfs, syzkaller-bugs

On Fri, Nov 29, 2019 at 11:19:08PM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    81b6b964 Merge branch 'master' of git://git.kernel.org/pub..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13b27696e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=773597fe8d7cb41a
> dashboard link: https://syzkaller.appspot.com/bug?extid=c732f8644185de340492
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 

It looks like the out_free_iclog: error path in xlog_alloc_log() doesn't
handle the case of a fully initialized iclog list. It uses an iclog !=
NULL check to terminate the freeing loop, and that might never occur if
we failed after the linked list was set up. I've confirmed with a simple
error injection test and will send a patch..

Brian

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+c732f8644185de340492@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: use-after-free in xlog_alloc_log+0x1398/0x14b0
> fs/xfs/xfs_log.c:1495
> Read of size 8 at addr ffff888068139890 by task syz-executor.3/32544
> 
> CPU: 0 PID: 32544 Comm: syz-executor.3 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118
>  print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
>  __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
>  kasan_report+0x12/0x20 mm/kasan/common.c:634
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
>  xlog_alloc_log+0x1398/0x14b0 fs/xfs/xfs_log.c:1495
>  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
>  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
>  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
>  mount_bdev+0x304/0x3c0 fs/super.c:1415
>  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
>  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
>  vfs_get_tree+0x8e/0x300 fs/super.c:1545
>  do_new_mount fs/namespace.c:2822 [inline]
>  do_mount+0x135a/0x1b50 fs/namespace.c:3142
>  ksys_mount+0xdb/0x150 fs/namespace.c:3351
>  __do_sys_mount fs/namespace.c:3365 [inline]
>  __se_sys_mount fs/namespace.c:3362 [inline]
>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
>  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x45d0ca
> Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 4d 8c fb ff c3 66 2e 0f
> 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 2a 8c fb ff c3 66 0f 1f 84 00 00 00 00 00
> RSP: 002b:00007f525b430a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007f525b430b40 RCX: 000000000045d0ca
> RDX: 00007f525b430ae0 RSI: 0000000020000100 RDI: 00007f525b430b00
> RBP: 0000000000000001 R08: 00007f525b430b40 R09: 00007f525b430ae0
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004
> R13: 00000000004ca258 R14: 00000000004e2870 R15: 00000000ffffffff
> 
> Allocated by task 32544:
>  save_stack+0x23/0x90 mm/kasan/common.c:69
>  set_track mm/kasan/common.c:77 [inline]
>  __kasan_kmalloc mm/kasan/common.c:510 [inline]
>  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
>  kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
>  __do_kmalloc mm/slab.c:3655 [inline]
>  __kmalloc+0x163/0x770 mm/slab.c:3664
>  kmalloc include/linux/slab.h:561 [inline]
>  kmem_alloc+0x15b/0x4d0 fs/xfs/kmem.c:21
>  kmem_zalloc fs/xfs/kmem.h:68 [inline]
>  xlog_alloc_log+0xcce/0x14b0 fs/xfs/xfs_log.c:1437
>  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
>  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
>  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
>  mount_bdev+0x304/0x3c0 fs/super.c:1415
>  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
>  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
>  vfs_get_tree+0x8e/0x300 fs/super.c:1545
>  do_new_mount fs/namespace.c:2822 [inline]
>  do_mount+0x135a/0x1b50 fs/namespace.c:3142
>  ksys_mount+0xdb/0x150 fs/namespace.c:3351
>  __do_sys_mount fs/namespace.c:3365 [inline]
>  __se_sys_mount fs/namespace.c:3362 [inline]
>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
>  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> 
> Freed by task 32544:
>  save_stack+0x23/0x90 mm/kasan/common.c:69
>  set_track mm/kasan/common.c:77 [inline]
>  kasan_set_free_info mm/kasan/common.c:332 [inline]
>  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
>  kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
>  __cache_free mm/slab.c:3425 [inline]
>  kfree+0x10a/0x2c0 mm/slab.c:3756
>  kvfree+0x61/0x70 mm/util.c:593
>  kmem_free fs/xfs/kmem.h:61 [inline]
>  xlog_alloc_log+0xeb5/0x14b0 fs/xfs/xfs_log.c:1497
>  xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
>  xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
>  xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
>  mount_bdev+0x304/0x3c0 fs/super.c:1415
>  xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
>  legacy_get_tree+0x108/0x220 fs/fs_context.c:647
>  vfs_get_tree+0x8e/0x300 fs/super.c:1545
>  do_new_mount fs/namespace.c:2822 [inline]
>  do_mount+0x135a/0x1b50 fs/namespace.c:3142
>  ksys_mount+0xdb/0x150 fs/namespace.c:3351
>  __do_sys_mount fs/namespace.c:3365 [inline]
>  __se_sys_mount fs/namespace.c:3362 [inline]
>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
>  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> 
> The buggy address belongs to the object at ffff888068139800
>  which belongs to the cache kmalloc-1k of size 1024
> The buggy address is located 144 bytes inside of
>  1024-byte region [ffff888068139800, ffff888068139c00)
> The buggy address belongs to the page:
> page:ffffea0001a04e40 refcount:1 mapcount:0 mapping:ffff8880aa400c40
> index:0x0
> raw: 00fffe0000000200 ffffea0002728148 ffffea00015604c8 ffff8880aa400c40
> raw: 0000000000000000 ffff888068139000 0000000100000002 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>  ffff888068139780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff888068139800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff888068139880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                          ^
>  ffff888068139900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888068139980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
> 
> 
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: KASAN: use-after-free Read in xlog_alloc_log (2)
       [not found] <20191130101340.14344-1-hdanton@sina.com>
@ 2019-12-02 21:16 ` Darrick J. Wong
  0 siblings, 0 replies; 3+ messages in thread
From: Darrick J. Wong @ 2019-12-02 21:16 UTC (permalink / raw)
  To: Hillf Danton; +Cc: syzbot, linux-kernel, linux-xfs, syzkaller-bugs

On Sat, Nov 30, 2019 at 06:13:40PM +0800, Hillf Danton wrote:
> 
> On Fri, 29 Nov 2019 23:19:08 -0800
> > Hello,
> > 
> > syzbot found the following crash on:
> > 
> > HEAD commit:    81b6b964 Merge branch 'master' of git://git.kernel.org/pub..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=13b27696e00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=773597fe8d7cb41a
> > dashboard link: https://syzkaller.appspot.com/bug?extid=c732f8644185de340492
> > compiler:       gcc (GCC) 9.0.0 20181231 (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+c732f8644185de340492@syzkaller.appspotmail.com
> > 
> > ==================================================================
> > BUG: KASAN: use-after-free in xlog_alloc_log+0x1398/0x14b0  
> > fs/xfs/xfs_log.c:1495
> > Read of size 8 at addr ffff888068139890 by task syz-executor.3/32544
> > 
> > CPU: 0 PID: 32544 Comm: syz-executor.3 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118
> >   print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
> >   __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
> >   kasan_report+0x12/0x20 mm/kasan/common.c:634
> >   __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
> >   xlog_alloc_log+0x1398/0x14b0 fs/xfs/xfs_log.c:1495
> >   xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
> >   xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
> >   xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
> >   mount_bdev+0x304/0x3c0 fs/super.c:1415
> >   xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
> >   legacy_get_tree+0x108/0x220 fs/fs_context.c:647
> >   vfs_get_tree+0x8e/0x300 fs/super.c:1545
> >   do_new_mount fs/namespace.c:2822 [inline]
> >   do_mount+0x135a/0x1b50 fs/namespace.c:3142
> >   ksys_mount+0xdb/0x150 fs/namespace.c:3351
> >   __do_sys_mount fs/namespace.c:3365 [inline]
> >   __se_sys_mount fs/namespace.c:3362 [inline]
> >   __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
> >   do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > RIP: 0033:0x45d0ca
> > Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 4d 8c fb ff c3 66 2e 0f  
> > 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff  
> > ff 0f 83 2a 8c fb ff c3 66 0f 1f 84 00 00 00 00 00
> > RSP: 002b:00007f525b430a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
> > RAX: ffffffffffffffda RBX: 00007f525b430b40 RCX: 000000000045d0ca
> > RDX: 00007f525b430ae0 RSI: 0000000020000100 RDI: 00007f525b430b00
> > RBP: 0000000000000001 R08: 00007f525b430b40 R09: 00007f525b430ae0
> > R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004
> > R13: 00000000004ca258 R14: 00000000004e2870 R15: 00000000ffffffff
> > 
> > Allocated by task 32544:
> >   save_stack+0x23/0x90 mm/kasan/common.c:69
> >   set_track mm/kasan/common.c:77 [inline]
> >   __kasan_kmalloc mm/kasan/common.c:510 [inline]
> >   __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
> >   kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
> >   __do_kmalloc mm/slab.c:3655 [inline]
> >   __kmalloc+0x163/0x770 mm/slab.c:3664
> >   kmalloc include/linux/slab.h:561 [inline]
> >   kmem_alloc+0x15b/0x4d0 fs/xfs/kmem.c:21
> >   kmem_zalloc fs/xfs/kmem.h:68 [inline]
> >   xlog_alloc_log+0xcce/0x14b0 fs/xfs/xfs_log.c:1437
> >   xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
> >   xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
> >   xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
> >   mount_bdev+0x304/0x3c0 fs/super.c:1415
> >   xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
> >   legacy_get_tree+0x108/0x220 fs/fs_context.c:647
> >   vfs_get_tree+0x8e/0x300 fs/super.c:1545
> >   do_new_mount fs/namespace.c:2822 [inline]
> >   do_mount+0x135a/0x1b50 fs/namespace.c:3142
> >   ksys_mount+0xdb/0x150 fs/namespace.c:3351
> >   __do_sys_mount fs/namespace.c:3365 [inline]
> >   __se_sys_mount fs/namespace.c:3362 [inline]
> >   __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
> >   do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > 
> > Freed by task 32544:
> >   save_stack+0x23/0x90 mm/kasan/common.c:69
> >   set_track mm/kasan/common.c:77 [inline]
> >   kasan_set_free_info mm/kasan/common.c:332 [inline]
> >   __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
> >   kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
> >   __cache_free mm/slab.c:3425 [inline]
> >   kfree+0x10a/0x2c0 mm/slab.c:3756
> >   kvfree+0x61/0x70 mm/util.c:593
> >   kmem_free fs/xfs/kmem.h:61 [inline]
> >   xlog_alloc_log+0xeb5/0x14b0 fs/xfs/xfs_log.c:1497
> >   xfs_log_mount+0xdc/0x780 fs/xfs/xfs_log.c:599
> >   xfs_mountfs+0xdb9/0x1be0 fs/xfs/xfs_mount.c:811
> >   xfs_fs_fill_super+0xd24/0x1750 fs/xfs/xfs_super.c:1732
> >   mount_bdev+0x304/0x3c0 fs/super.c:1415
> >   xfs_fs_mount+0x35/0x40 fs/xfs/xfs_super.c:1806
> >   legacy_get_tree+0x108/0x220 fs/fs_context.c:647
> >   vfs_get_tree+0x8e/0x300 fs/super.c:1545
> >   do_new_mount fs/namespace.c:2822 [inline]
> >   do_mount+0x135a/0x1b50 fs/namespace.c:3142
> >   ksys_mount+0xdb/0x150 fs/namespace.c:3351
> >   __do_sys_mount fs/namespace.c:3365 [inline]
> >   __se_sys_mount fs/namespace.c:3362 [inline]
> >   __x64_sys_mount+0xbe/0x150 fs/namespace.c:3362
> >   do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > 
> > The buggy address belongs to the object at ffff888068139800
> >   which belongs to the cache kmalloc-1k of size 1024
> > The buggy address is located 144 bytes inside of
> >   1024-byte region [ffff888068139800, ffff888068139c00)
> > The buggy address belongs to the page:
> > page:ffffea0001a04e40 refcount:1 mapcount:0 mapping:ffff8880aa400c40  
> > index:0x0
> > raw: 00fffe0000000200 ffffea0002728148 ffffea00015604c8 ffff8880aa400c40
> > raw: 0000000000000000 ffff888068139000 0000000100000002 0000000000000000
> > page dumped because: kasan: bad access detected
> > 
> > Memory state around the buggy address:
> >   ffff888068139780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >   ffff888068139800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > ffff888068139880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >                           ^
> >   ffff888068139900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >   ffff888068139980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ==================================================================
> 
> Add check of ring end to avoid repeated free.
> 
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1495,6 +1495,8 @@ out_free_iclog:
>  		prev_iclog = iclog->ic_next;
>  		kmem_free(iclog->ic_data);
>  		kmem_free(iclog);
> +		if (prev_iclog == log->l_iclog) /* complete ring */
> +			break;

This is probably true, but I can't review or commit this without an SOB.

--D

>  	}
>  out_free_log:
>  	kmem_free(log);
> 

^ permalink raw reply	[flat|nested] 3+ messages in thread

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Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-30  7:19 KASAN: use-after-free Read in xlog_alloc_log (2) syzbot
2019-12-03 13:48 ` Brian Foster
     [not found] <20191130101340.14344-1-hdanton@sina.com>
2019-12-02 21:16 ` Darrick J. Wong

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