[moderation] [fs?] kernel BUG in vfs_get_tree

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 523b23f0bee3 Add linux-next specific files for 20240710
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13e7da4e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=98dd8c4bab5cdce
dashboard link: https://syzkaller.appspot.com/bug?extid=111c8af1477ec346f6b0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/345bcd25ed2f/disk-523b23f0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a4508962d345/vmlinux-523b23f0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4ba5eb555639/bzImage-523b23f0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+111c8a...@syzkaller.appspotmail.com

Filesystem bcachefs get_tree() didn't set fc->root
------------[ cut here ]------------
kernel BUG at fs/super.c:1799!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 5444 Comm: syz.0.57 Not tainted 6.10.0-rc7-next-20240710-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:vfs_get_tree+0x29c/0x2a0 fs/super.c:1799
Code: ff 49 8b 1f 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 24 92 ee ff 48 8b 33 48 c7 c7 20 af d8 8b e8 b5 1c 84 09 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f
RSP: 0018:ffffc900050bfd08 EFLAGS: 00010246
RAX: 0000000000000032 RBX: ffffffff8e945140 RCX: c2e659a015266e00
RDX: ffffc900036b1000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: 1ffff110049d0d96 R08: ffffffff8173e319 R09: 1ffff92000a17f3c
R10: dffffc0000000000 R11: fffff52000a17f3d R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888024e86cb0 R15: ffff888024e86c98
FS: 00007f334a3426c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2607aa CR3: 000000002d468000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
do_new_mount+0x2be/0xb40 fs/namespace.c:3471
do_mount fs/namespace.c:3811 [inline]
__do_sys_mount fs/namespace.c:4019 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3996
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f33495772da
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 7e 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f334a341e78 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f334a341f00 RCX: 00007f33495772da
RDX: 0000000020011a00 RSI: 0000000020011a40 RDI: 00007f334a341ec0
RBP: 0000000020011a00 R08: 00007f334a341f00 R09: 0000000001200014
R10: 0000000001200014 R11: 0000000000000206 R12: 0000000020011a40
R13: 00007f334a341ec0 R14: 0000000000011a00 R15: 0000000020000240
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vfs_get_tree+0x29c/0x2a0 fs/super.c:1799
Code: ff 49 8b 1f 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 24 92 ee ff 48 8b 33 48 c7 c7 20 af d8 8b e8 b5 1c 84 09 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f
RSP: 0018:ffffc900050bfd08 EFLAGS: 00010246
RAX: 0000000000000032 RBX: ffffffff8e945140 RCX: c2e659a015266e00
RDX: ffffc900036b1000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: 1ffff110049d0d96 R08: ffffffff8173e319 R09: 1ffff92000a17f3c
R10: dffffc0000000000 R11: fffff52000a17f3d R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888024e86cb0 R15: ffff888024e86c98
FS: 00007f334a3426c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49010d1178 CR3: 000000002d468000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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