Re: virtiofs: WARN_ON(out_sgs + in_sgs != total_sgs)

From: Qian Cai
Date: Fri Oct 02 2020 - 22:44:57 EST

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On Fri, 2020-10-02 at 12:28 -0400, Qian Cai wrote:
> Running some fuzzing on virtiofs from a non-privileged user could trigger a
> warning in virtio_fs_enqueue_req():
>
> WARN_ON(out_sgs + in_sgs != total_sgs);

Okay, I can reproduce this after running for a few hours:

out_sgs = 3, in_sgs = 2, total_sgs = 6

and this time from flush_bg_queue() instead of fuse_simple_request().

>From the log, the last piece of code is:

ftruncate(fd=186, length=4)

which is a test file on virtiofs:

[main] testfile fd:186 filename:trinity-testfile3 flags:2 fopened:1 fcntl_flags:2000 global:1
[main] start: 0x7f47c1199000 size:4KB name: trinity-testfile3 global:1

[ 9863.468502] WARNING: CPU: 16 PID: 286083 at fs/fuse/virtio_fs.c:1152 virtio_fs_enqueue_req+0xd36/0xde0 [virtiofs]
[ 9863.474442] Modules linked in: dlci 8021q garp mrp bridge stp llc ieee802154_socket ieee802154 vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vsock mpls_router vmw_vmci ip_tunnel as
[ 9863.474555] ata_piix fuse serio_raw libata e1000 sunrpc dm_mirror dm_region_hash dm_log dm_mod
[ 9863.535805] CPU: 16 PID: 286083 Comm: trinity-c5 Kdump: loaded Not tainted 5.9.0-rc7-next-20201002+ #2
[ 9863.544368] Hardware name: Red Hat KVM, BIOS 1.14.0-1.module+el8.3.0+7638+07cf13d2 04/01/2014
[ 9863.550129] RIP: 0010:virtio_fs_enqueue_req+0xd36/0xde0 [virtiofs]
[ 9863.552998] Code: 60 09 23 d9 e9 44 fa ff ff e8 56 09 23 d9 e9 70 fa ff ff 48 89 cf 48 89 4c 24 08 e8 44 09 23 d9 48 8b 4c 24 08 e9 7c fa ff ff <0f> 0b 48 c7 c7 c0 85 60 c0 44 89 e1 44 89 fa 44 89 ee e8 e3 b7
[ 9863.561720] RSP: 0018:ffff888a696ef6f8 EFLAGS: 00010202
[ 9863.565420] RAX: 0000000000000000 RBX: ffff88892e030008 RCX: 0000000000000000
[ 9863.568735] RDX: 0000000000000005 RSI: 0000000000000000 RDI: ffff888a696ef8ac
[ 9863.572037] RBP: ffff888a49d03d30 R08: ffffed114d2ddf18 R09: ffff888a696ef8a0
[ 9863.575383] R10: ffff888a696ef8bf R11: ffffed114d2ddf17 R12: 0000000000000006
[ 9863.578668] R13: 0000000000000003 R14: 0000000000000002 R15: 0000000000000002
[ 9863.581971] FS: 00007f47c12f5740(0000) GS:ffff888a7f800000(0000) knlGS:0000000000000000
[ 9863.585752] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9863.590232] CR2: 0000000000000000 CR3: 0000000a63570005 CR4: 0000000000770ee0
[ 9863.594698] DR0: 00007f6642e43000 DR1: 0000000000000000 DR2: 0000000000000000
[ 9863.598521] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
[ 9863.601861] PKRU: 55555540
[ 9863.603173] Call Trace:
[ 9863.604382] ? virtio_fs_probe+0x13e0/0x13e0 [virtiofs]
[ 9863.606838] ? is_bpf_text_address+0x21/0x30
[ 9863.608869] ? kernel_text_address+0x125/0x140
[ 9863.610962] ? __kernel_text_address+0xe/0x30
[ 9863.613117] ? unwind_get_return_address+0x5f/0xa0
[ 9863.615427] ? create_prof_cpu_mask+0x20/0x20
[ 9863.617435] ? _raw_write_lock_irqsave+0xe0/0xe0
[ 9863.619627] virtio_fs_wake_pending_and_unlock+0x1ea/0x610 [virtiofs]
[ 9863.622638] ? queue_request_and_unlock+0x115/0x280 [fuse]
[ 9863.625224] flush_bg_queue+0x24c/0x3e0 [fuse]
[ 9863.627325] fuse_simple_background+0x3d7/0x6c0 [fuse]
[ 9863.629735] fuse_send_writepage+0x173/0x420 [fuse]
[ 9863.632031] fuse_flush_writepages+0x1fe/0x330 [fuse]
[ 9863.634463] ? make_kgid+0x13/0x20
[ 9863.636064] ? fuse_change_attributes_common+0x2de/0x940 [fuse]
[ 9863.638850] fuse_do_setattr+0xe84/0x13c0 [fuse]
[ 9863.641024] ? migrate_swap_stop+0x8d1/0x920
[ 9863.643041] ? fuse_flush_times+0x390/0x390 [fuse]
[ 9863.645347] ? avc_has_perm_noaudit+0x390/0x390
[ 9863.647465] fuse_setattr+0x197/0x400 [fuse]
[ 9863.649466] notify_change+0x744/0xda0
[ 9863.651247] ? __down_timeout+0x2a0/0x2a0
[ 9863.653125] ? do_truncate+0xe2/0x180
[ 9863.654854] do_truncate+0xe2/0x180
[ 9863.656509] ? __x64_sys_openat2+0x1c0/0x1c0
[ 9863.658512] ? alarm_setitimer+0xa0/0x110
[ 9863.660418] do_sys_ftruncate+0x1ee/0x2c0
[ 9863.662311] do_syscall_64+0x33/0x40
[ 9863.663980] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 9863.666384] RIP: 0033:0x7f47c0c0878d
[ 9863.668061] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 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 8b 0d cb 56 2c 00 f7 d8 64 89 08
[ 9863.676717] RSP: 002b:00007fff515c2598 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
[ 9863.680226] RAX: ffffffffffffffda RBX: 000000000000004d RCX: 00007f47c0c0878d
[ 9863.688055] RDX: 0000000000800000 RSI: 0000000000000004 RDI: 00000000000000ba
[ 9863.693672] RBP: 000000000000004d R08: 000000000000003a R09: 0000000000000001
[ 9863.699423] R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000000002
[ 9863.708897] R13: 00007f47c12cb058 R14: 00007f47c12f56c0 R15: 00007f47c12cb000
[ 9863.713106] CPU: 16 PID: 286083 Comm: trinity-c5 Kdump: loaded Not tainted 5.9.0-rc7-next-20201002+ #2
[ 9863.717465] Hardware name: Red Hat KVM, BIOS 1.14.0-1.module+el8.3.0+7638+07cf13d2 04/01/2014
[ 9863.721389] Call Trace:
[ 9863.722547] dump_stack+0x7c/0xa2
[ 9863.724110] __warn.cold.13+0xe/0x47
[ 9863.725804] ? virtio_fs_enqueue_req+0xd36/0xde0 [virtiofs]
[ 9863.728427] report_bug+0x1af/0x260
[ 9863.730054] handle_bug+0x44/0x80
[ 9863.731652] exc_invalid_op+0x13/0x40
[ 9863.734911] asm_exc_invalid_op+0x12/0x20
[ 9863.736940] RIP: 0010:virtio_fs_enqueue_req+0xd36/0xde0 [virtiofs]
[ 9863.739833] Code: 60 09 23 d9 e9 44 fa ff ff e8 56 09 23 d9 e9 70 fa ff ff 48 89 cf 48 89 4c 24 08 e8 44 09 23 d9 48 8b 4c 24 08 e9 7c fa ff ff <0f> 0b 48 c7 c7 c0 85 60 c0 44 89 e1 44 89 fa 44 89 ee e8 e3 b7
[ 9863.748519] RSP: 0018:ffff888a696ef6f8 EFLAGS: 00010202
[ 9863.750935] RAX: 0000000000000000 RBX: ffff88892e030008 RCX: 0000000000000000
[ 9863.754247] RDX: 0000000000000005 RSI: 0000000000000000 RDI: ffff888a696ef8ac
[ 9863.760885] RBP: ffff888a49d03d30 R08: ffffed114d2ddf18 R09: ffff888a696ef8a0
[ 9863.764814] R10: ffff888a696ef8bf R11: ffffed114d2ddf17 R12: 0000000000000006
[ 9863.768148] R13: 0000000000000003 R14: 0000000000000002 R15: 0000000000000002
[ 9863.771492] ? virtio_fs_probe+0x13e0/0x13e0 [virtiofs]
[ 9863.773950] ? is_bpf_text_address+0x21/0x30
[ 9863.775979] ? kernel_text_address+0x125/0x140
[ 9863.778061] ? __kernel_text_address+0xe/0x30
[ 9863.780124] ? unwind_get_return_address+0x5f/0xa0
[ 9863.782395] ? create_prof_cpu_mask+0x20/0x20
[ 9863.784451] ? _raw_write_lock_irqsave+0xe0/0xe0
[ 9863.786602] virtio_fs_wake_pending_and_unlock+0x1ea/0x610 [virtiofs]
[ 9863.789614] ? queue_request_and_unlock+0x115/0x280 [fuse]
[ 9863.792178] flush_bg_queue+0x24c/0x3e0 [fuse]
[ 9863.796678] fuse_simple_background+0x3d7/0x6c0 [fuse]
[ 9863.802329] fuse_send_writepage+0x173/0x420 [fuse]
[ 9863.808342] fuse_flush_writepages+0x1fe/0x330 [fuse]
[ 9863.812086] ? make_kgid+0x13/0x20
[ 9863.813681] ? fuse_change_attributes_common+0x2de/0x940 [fuse]
[ 9863.816465] fuse_do_setattr+0xe84/0x13c0 [fuse]
[ 9863.819633] ? migrate_swap_stop+0x8d1/0x920
[ 9863.824285] ? fuse_flush_times+0x390/0x390 [fuse]
[ 9863.827331] ? avc_has_perm_noaudit+0x390/0x390
[ 9863.875278] fuse_setattr+0x197/0x400 [fuse]
[ 9863.878496] notify_change+0x744/0xda0
[ 9863.880640] ? __down_timeout+0x2a0/0x2a0
[ 9863.882960] ? do_truncate+0xe2/0x180
[ 9863.886311] do_truncate+0xe2/0x180
[ 9863.888392] ? __x64_sys_openat2+0x1c0/0x1c0
[ 9863.890418] ? alarm_setitimer+0xa0/0x110
[ 9863.894430] do_sys_ftruncate+0x1ee/0x2c0
[ 9863.896468] do_syscall_64+0x33/0x40
[ 9863.898167] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 9863.901089] RIP: 0033:0x7f47c0c0878d
[ 9863.903447] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 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 8b 0d cb 56 2c 00 f7 d8 64 89 08
[ 9863.914356] RSP: 002b:00007fff515c2598 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
[ 9863.917998] RAX: ffffffffffffffda RBX: 000000000000004d RCX: 00007f47c0c0878d
[ 9863.921364] RDX: 0000000000800000 RSI: 0000000000000004 RDI: 00000000000000ba
[ 9863.928285] RBP: 000000000000004d R08: 000000000000003a R09: 0000000000000001
[ 9863.932523] R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000000002
[ 9863.935835] R13: 00007f47c12cb058 R14: 00007f47c12f56c0 R15: 00007f47c12cb000
[ 9863.939183] ---[ end trace f6f5d958c186bcee ]---

Next message: kernel test robot: "include/linux/sched/topology.h:237:9: error: implicit declaration of function 'cpu_logical_map'"
Previous message: Yonghong Song: "Re: [PATCH][next] bpf: verifier: Use fallthrough pseudo-keyword"
In reply to: Qian Cai: "virtiofs: WARN_ON(out_sgs + in_sgs != total_sgs)"
Next in thread: Vivek Goyal: "Re: virtiofs: WARN_ON(out_sgs + in_sgs != total_sgs)"
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