Re: WARNING in md_alloc

[Yu Kuai <yukuai1@huaweicloud.com>]

在 2022/08/28 22:34, Jiacheng Xu 写道:
> Hello,
> 
> When using modified Syzkaller to fuzz the Linux kernel-5.15.58, the
> following crash was triggered.
> 
> HEAD commit: 568035b01cfb Linux-5.15.58
> git tree: upstream
> 
> console output:
> https://drive.google.com/file/d/1FU_URJHWwRs2KtNZ26WzxlSGE95DWBxe/view?usp=sharing
> kernel config: https://drive.google.com/file/d/1wgIUDwP5ho29AM-K7HhysSTfWFpfXYkG/view?usp=sharing
> syz repro: https://drive.google.com/file/d/1RYMFWOThdDCrjoFgRZrzfzXJP2AjHOLW/view?usp=sharing
> C reproducer: https://drive.google.com/file/d/1ODU9zL9mWsfjlQJzz4WjS8IfDlvt_68F/view?usp=sharing
> 
> Environment:
> Ubuntu 20.04 on Linux 5.4.0
> QEMU 4.2.1:
> qemu-system-x86_64 \
>    -m 2G \
>    -smp 2 \
>    -kernel /home/workdir/bzImage \
>    -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0" \
>    -drive file=/home/workdir/stretch.img,format=raw \
>    -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10021-:22 \
>    -net nic,model=e1000 \
>    -enable-kvm \
>    -nographic \
>    -pidfile vm.pid \
>    2>&1 | tee vm.log
> 
> If you fix this issue, please add the following tag to the commit:
> Reported-by:  Jiacheng Xu<stitch@zju.edu.cn>
> 
> ==========================================================
> loop7: detected capacity change from 0 to 96
> NILFS (loop7): broken superblock, retrying with spare superblock
> (blocksize = 1024)
> NILFS (loop7): broken superblock, retrying with spare superblock
> (blocksize = 2048)
> NILFS (loop7): mounting unchecked fs
> NILFS (loop7): recovery complete
> sp0: Synchronizing with TNC
> FAULT_INJECTION: forcing a failure.
> name failslab, interval 1, probability 0, space 0, times 1
> CPU: 2 PID: 7259 Comm: syz-executor Not tainted 5.15.58 #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.13.0-1ubuntu1.1 04/01/2014
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x8b/0xb3 lib/dump_stack.c:106
>   fail_dump lib/fault-inject.c:52 [inline]
>   should_fail.cold+0x5/0xa lib/fault-inject.c:146
>   should_failslab+0x5/0x10 mm/slab_common.c:1337
>   slab_pre_alloc_hook mm/slab.h:494 [inline]
>   slab_alloc_node mm/slub.c:3129 [inline]
>   slab_alloc mm/slub.c:3223 [inline]
>   kmem_cache_alloc+0x4e/0x820 mm/slub.c:3228
>   kmem_cache_zalloc include/linux/slab.h:711 [inline]
>   __kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:593
>   kernfs_new_node+0x93/0x120 fs/kernfs/dir.c:655
>   __kernfs_create_file+0x51/0x350 fs/kernfs/file.c:985
>   sysfs_add_file_mode_ns+0x226/0x540 fs/sysfs/file.c:317
>   sysfs_create_file_ns+0x131/0x1c0 fs/sysfs/file.c:343
>   sysfs_create_file include/linux/sysfs.h:607 [inline]
>   device_create_file+0xe6/0x1d0 drivers/base/core.c:2762
>   device_add+0x5b0/0x1d40 drivers/base/core.c:3338
>   device_add_disk+0x2fd/0xf90 block/genhd.c:446
>   add_disk include/linux/genhd.h:212 [inline]
>   md_alloc+0x947/0x11c0 drivers/md/md.c:5714
>   md_probe+0x69/0x70 drivers/md/md.c:5744
>   blk_request_module+0x111/0x1d0 block/genhd.c:681
>   blkdev_get_no_open+0x178/0x1e0 block/bdev.c:740
>   blkdev_get_by_dev block/bdev.c:804 [inline]
>   blkdev_get_by_dev+0x73/0x900 block/bdev.c:790
>   swsusp_check+0x97/0x2f0 kernel/power/swap.c:1526
>   software_resume kernel/power/hibernate.c:977 [inline]
>   software_resume+0x124/0x230 kernel/power/hibernate.c:912
>   resume_store+0xf1/0x130 kernel/power/hibernate.c:1179
>   kobj_attr_store+0x50/0x80 lib/kobject.c:856
>   sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
>   kernfs_fop_write_iter+0x337/0x500 fs/kernfs/file.c:296
>   call_write_iter include/linux/fs.h:2087 [inline]
>   new_sync_write+0x432/0x660 fs/read_write.c:507
>   vfs_write+0x67a/0xae0 fs/read_write.c:594
>   ksys_write+0x12d/0x250 fs/read_write.c:647
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x61/0xcb
> RIP: 0033:0x7f85eaf61dfd
> Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007f85e84c9c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f85eb0880a0 RCX: 00007f85eaf61dfd
> RDX: 000000000000fdef RSI: 0000000020002500 RDI: 000000000000000d
> RBP: 00007f85e84c9c90 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001a
> R13: 00007ffe899206df R14: 00007ffe89920880 R15: 00007f85e84c9dc0
>   </TASK>
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 7259 at block/genhd.c:544
> device_add_disk+0x383/0xf90 block/genhd.c:544
> Modules linked in:
> CPU: 2 PID: 7259 Comm: syz-executor Not tainted 5.15.58 #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.13.0-1ubuntu1.1 04/01/2014
> RIP: 0010:device_add_disk+0x383/0xf90 block/genhd.c:544
> Code: 74 08 3c 03 0f 8e 02 0a 00 00 8b 5d 00 bf 03 01 00 00 89 de e8
> 1e 2b a6 fd 81 fb 03 01 00 00 0f 84 3b 02 00 00 e8 ad 29 a6 fd <0f> 0b
> 41 bc 01 00 00 00 e8 a0 29 a6 fd 44 89 e0 48 83 c4 38 5b 5d
> RSP: 0018:ffffc9000826fa08 EFLAGS: 00010246
> RAX: 0000000000040000 RBX: 0000000000000009 RCX: 0000000000040000
> RDX: ffffc900018d1000 RSI: ffff888108590000 RDI: 0000000000000002
> RBP: ffff888104e6e000 R08: ffffffff83d022a3 R09: 0000000000000103
> R10: 0000000000000005 R11: ffffed1021112187 R12: 00000000fffffff4
> R13: ffff888108890c00 R14: ffff888104e6e004 R15: ffff888104e6e080
> FS:  00007f85e84ca700(0000) GS:ffff888063f00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000560a42f27150 CR3: 0000000016364000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <TASK>
>   add_disk include/linux/genhd.h:212 [inline]
>   md_alloc+0x947/0x11c0 drivers/md/md.c:5714
>   md_probe+0x69/0x70 drivers/md/md.c:5744
>   blk_request_module+0x111/0x1d0 block/genhd.c:681
>   blkdev_get_no_open+0x178/0x1e0 block/bdev.c:740
>   blkdev_get_by_dev block/bdev.c:804 [inline]
>   blkdev_get_by_dev+0x73/0x900 block/bdev.c:790
>   swsusp_check+0x97/0x2f0 kernel/power/swap.c:1526
>   software_resume kernel/power/hibernate.c:977 [inline]
>   software_resume+0x124/0x230 kernel/power/hibernate.c:912
>   resume_store+0xf1/0x130 kernel/power/hibernate.c:1179
>   kobj_attr_store+0x50/0x80 lib/kobject.c:856
>   sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
>   kernfs_fop_write_iter+0x337/0x500 fs/kernfs/file.c:296
>   call_write_iter include/linux/fs.h:2087 [inline]
>   new_sync_write+0x432/0x660 fs/read_write.c:507
>   vfs_write+0x67a/0xae0 fs/read_write.c:594
>   ksys_write+0x12d/0x250 fs/read_write.c:647
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x61/0xcb
> RIP: 0033:0x7f85eaf61dfd
> Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007f85e84c9c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f85eb0880a0 RCX: 00007f85eaf61dfd
> RDX: 000000000000fdef RSI: 0000000020002500 RDI: 000000000000000d
> RBP: 00007f85e84c9c90 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001a
> R13: 00007ffe899206df R14: 00007ffe89920880 R15: 00007f85e84c9dc0
>   </TASK>
> .
> 

This is just a WARN_ON() that is triggered because memory alloc failure
is injected. And this is not a problem now that add_disk() has
appropriate error handling.

Thanks,
Kuai