Date:   Tue, 16 Mar 2021 02:32:11 -0400
From:   Douglas Gilbert <dgilbert@...erlog.com>
To:     syzbot <syzbot+0a0e8ecea895d38332e6@...kaller.appspotmail.com>,
        jejb@...ux.ibm.com, linux-kernel@...r.kernel.org,
        linux-scsi@...r.kernel.org, martin.petersen@...cle.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] KASAN: invalid-free in sg_finish_scsi_blk_rq

On 2021-03-15 9:59 p.m., syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d98f554b Add linux-next specific files for 20210312
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1189318ad00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e362835d2e58cef6
> dashboard link: https://syzkaller.appspot.com/bug?extid=0a0e8ecea895d38332e6
> 
> Unfortunately, I don't have any reproducer for this issue yet.

No need, I think I can see how it happens. A particular type of resource
error from the block layer, together with a 32 byte (or larger) SCSI
command. I'm testing a patch.

Doug Gilbert

> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+0a0e8ecea895d38332e6@...kaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: double-free or invalid-free in slab_free mm/slub.c:3161 [inline]
> BUG: KASAN: double-free or invalid-free in kfree+0xe5/0x7f0 mm/slub.c:4215
> 
> CPU: 0 PID: 10481 Comm: syz-executor.5 Not tainted 5.12.0-rc2-next-20210312-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:79 [inline]
>   dump_stack+0x141/0x1d7 lib/dump_stack.c:120
>   print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
>   kasan_report_invalid_free+0x51/0x80 mm/kasan/report.c:357
>   ____kasan_slab_free mm/kasan/common.c:340 [inline]
>   __kasan_slab_free+0x118/0x130 mm/kasan/common.c:367
>   kasan_slab_free include/linux/kasan.h:200 [inline]
>   slab_free_hook mm/slub.c:1562 [inline]
>   slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
>   slab_free mm/slub.c:3161 [inline]
>   kfree+0xe5/0x7f0 mm/slub.c:4215
>   scsi_req_free_cmd include/scsi/scsi_request.h:28 [inline]
>   sg_finish_scsi_blk_rq+0x690/0x810 drivers/scsi/sg.c:3224
>   sg_common_write+0xa07/0xe70 drivers/scsi/sg.c:1132
>   sg_v3_submit+0x3b1/0x530 drivers/scsi/sg.c:797
>   sg_ctl_sg_io drivers/scsi/sg.c:1785 [inline]
>   sg_ioctl_common+0x3c86/0x97f0 drivers/scsi/sg.c:2014
>   sg_ioctl+0x7c/0x110 drivers/scsi/sg.c:2229
>   vfs_ioctl fs/ioctl.c:48 [inline]
>   __do_sys_ioctl fs/ioctl.c:753 [inline]
>   __se_sys_ioctl fs/ioctl.c:739 [inline]
>   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
>   do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x465f69
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f8413efa188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465f69
> RDX: 0000000020001780 RSI: 0000000000002285 RDI: 0000000000000003
> RBP: 00000000004bfa8f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
> R13: 00007ffe20e16e2f R14: 00007f8413efa300 R15: 0000000000022000
> 
> Allocated by task 10481:
>   kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>   kasan_set_track mm/kasan/common.c:46 [inline]
>   set_alloc_info mm/kasan/common.c:427 [inline]
>   ____kasan_kmalloc mm/kasan/common.c:506 [inline]
>   ____kasan_kmalloc mm/kasan/common.c:465 [inline]
>   __kasan_kmalloc+0x99/0xc0 mm/kasan/common.c:515
>   kmalloc include/linux/slab.h:561 [inline]
>   kzalloc include/linux/slab.h:686 [inline]
>   sg_start_req+0x16f/0x24e0 drivers/scsi/sg.c:3044
>   sg_common_write+0x5fd/0xe70 drivers/scsi/sg.c:1109
>   sg_v3_submit+0x3b1/0x530 drivers/scsi/sg.c:797
>   sg_ctl_sg_io drivers/scsi/sg.c:1785 [inline]
>   sg_ioctl_common+0x3c86/0x97f0 drivers/scsi/sg.c:2014
>   sg_ioctl+0x7c/0x110 drivers/scsi/sg.c:2229
>   vfs_ioctl fs/ioctl.c:48 [inline]
>   __do_sys_ioctl fs/ioctl.c:753 [inline]
>   __se_sys_ioctl fs/ioctl.c:739 [inline]
>   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
>   do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Freed by task 10481:
>   kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>   kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
>   kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
>   ____kasan_slab_free mm/kasan/common.c:360 [inline]
>   ____kasan_slab_free mm/kasan/common.c:325 [inline]
>   __kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
>   kasan_slab_free include/linux/kasan.h:200 [inline]
>   slab_free_hook mm/slub.c:1562 [inline]
>   slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
>   slab_free mm/slub.c:3161 [inline]
>   kfree+0xe5/0x7f0 mm/slub.c:4215
>   sg_start_req+0x1b33/0x24e0 drivers/scsi/sg.c:3106
>   sg_common_write+0x5fd/0xe70 drivers/scsi/sg.c:1109
>   sg_v3_submit+0x3b1/0x530 drivers/scsi/sg.c:797
>   sg_ctl_sg_io drivers/scsi/sg.c:1785 [inline]
>   sg_ioctl_common+0x3c86/0x97f0 drivers/scsi/sg.c:2014
>   sg_ioctl+0x7c/0x110 drivers/scsi/sg.c:2229
>   vfs_ioctl fs/ioctl.c:48 [inline]
>   __do_sys_ioctl fs/ioctl.c:753 [inline]
>   __se_sys_ioctl fs/ioctl.c:739 [inline]
>   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
>   do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Last potentially related work creation:
>   kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>   kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
>   kvfree_call_rcu+0x74/0x8c0 kernel/rcu/tree.c:3597
>   drop_sysctl_table+0x3c0/0x4e0 fs/proc/proc_sysctl.c:1646
>   unregister_sysctl_table fs/proc/proc_sysctl.c:1684 [inline]
>   unregister_sysctl_table+0xc2/0x190 fs/proc/proc_sysctl.c:1659
>   mpls_dev_sysctl_unregister net/mpls/af_mpls.c:1442 [inline]
>   mpls_dev_notify+0x64d/0x8b0 net/mpls/af_mpls.c:1632
>   notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
>   call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2063
>   call_netdevice_notifiers_extack net/core/dev.c:2075 [inline]
>   call_netdevice_notifiers net/core/dev.c:2089 [inline]
>   dev_change_name+0x447/0x690 net/core/dev.c:1346
>   do_setlink+0x2c1f/0x3a70 net/core/rtnetlink.c:2688
>   __rtnl_newlink+0xdc6/0x1710 net/core/rtnetlink.c:3376
>   rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3491
>   rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553
>   netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502
>   netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
>   netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
>   netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
>   sock_sendmsg_nosec net/socket.c:654 [inline]
>   sock_sendmsg+0xcf/0x120 net/socket.c:674
>   __sys_sendto+0x21c/0x320 net/socket.c:1977
>   __do_sys_sendto net/socket.c:1989 [inline]
>   __se_sys_sendto net/socket.c:1985 [inline]
>   __x64_sys_sendto+0xdd/0x1b0 net/socket.c:1985
>   do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> The buggy address belongs to the object at ffff88802ae5f400
>   which belongs to the cache kmalloc-256 of size 256
> The buggy address is located 0 bytes inside of
>   256-byte region [ffff88802ae5f400, ffff88802ae5f500)
> The buggy address belongs to the page:
> page:ffffea0000ab9780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ae5e
> head:ffffea0000ab9780 order:1 compound_mapcount:0
> flags: 0xfff00000010200(slab|head)
> raw: 00fff00000010200 0000000000000000 0000000600000001 ffff888010841b40
> raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>   ffff88802ae5f300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>   ffff88802ae5f380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>> ffff88802ae5f400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                     ^
>   ffff88802ae5f480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff88802ae5f500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
> 
> 
> ---
> This report 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@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 

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