[syzbot] [bcachefs?] kernel BUG in cpu_replicas_add_entry

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cf87f46fd34d Merge tag 'drm-fixes-2024-05-11' of https://g..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=148f37bc980000
kernel config: https://syzkaller.appspot.com/x/.config?x=9d7ea7de0cb32587
dashboard link: https://syzkaller.appspot.com/bug?extid=73414091bd382684ee2b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=159e243f180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1460fc5c980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9c147953fc8e/disk-cf87f46f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a55c9d1f91fc/vmlinux-cf87f46f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f8dab47ae8c2/bzImage-cf87f46f.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7ca4b9223f48/mount_0.gz

The issue was bisected to:

commit 03ef80b469d5d83530ce1ce15be78a40e5300f9b
Author: Kent Overstreet <kent.ov...@linux.dev>
Date: Sat Sep 23 22:41:51 2023 +0000

bcachefs: Ignore unknown mount options

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=176de750980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=14ede750980000
console output: https://syzkaller.appspot.com/x/log.txt?x=10ede750980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+734140...@syzkaller.appspotmail.com
Fixes: 03ef80b469d5 ("bcachefs: Ignore unknown mount options")

loop0: detected capacity change from 0 to 32768
bcachefs (loop0): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
bcachefs (loop0): recovering from clean shutdown, journal seq 10
------------[ cut here ]------------
kernel BUG at fs/bcachefs/replicas.c:205!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 5075 Comm: syz-executor128 Not tainted 6.9.0-rc7-syzkaller-00183-gcf87f46fd34d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:cpu_replicas_add_entry+0x6c8/0x6f0 fs/bcachefs/replicas.c:205
Code: 24 18 e8 ab 22 be fd e9 57 fd ff ff e8 f1 c5 5c fd 90 0f 0b e8 e9 c5 5c fd 90 0f 0b e8 e1 c5 5c fd 90 0f 0b e8 d9 c5 5c fd 90 <0f> 0b e8 d1 c5 5c fd 90 0f 0b e8 c9 c5 5c fd 90 0f 0b e8 c1 c5 5c
RSP: 0018:ffffc9000346ef18 EFLAGS: 00010293
RAX: ffffffff843941b7 RBX: dffffc0000000000 RCX: ffff888023cd5a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff84393d28 R09: ffffffff843804ad
R10: 0000000000000007 R11: ffff888023cd5a00 R12: 1ffff1100eb70101
R13: ffff888071e440a3 R14: 0000000000000000 R15: ffff888071e440a0
FS: 000055556e8b0380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561d03c02678 CR3: 0000000074648000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bch2_replicas_set_usage+0x3cf/0x710 fs/bcachefs/replicas.c:630
journal_replay_early+0xba/0x4f0 fs/bcachefs/recovery.c:411
bch2_fs_recovery+0x39c2/0x63b0 fs/bcachefs/recovery.c:747
bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1043
bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2105
bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1903
legacy_get_tree+0xee/0x190 fs/fs_context.c:662
vfs_get_tree+0x90/0x2a0 fs/super.c:1779
do_new_mount+0x2be/0xb40 fs/namespace.c:3352
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efe923c2b7a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffec93a6af8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffec93a6b10 RCX: 00007efe923c2b7a
RDX: 0000000020011a00 RSI: 0000000020011a40 RDI: 00007ffec93a6b10
RBP: 0000000000000004 R08: 00007ffec93a6b50 R09: 0066666666666666
R10: 0000000001200014 R11: 0000000000000282 R12: 0000000001200014
R13: 00007ffec93a6b50 R14: 0000000000000003 R15: 0000000001000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:cpu_replicas_add_entry+0x6c8/0x6f0 fs/bcachefs/replicas.c:205
Code: 24 18 e8 ab 22 be fd e9 57 fd ff ff e8 f1 c5 5c fd 90 0f 0b e8 e9 c5 5c fd 90 0f 0b e8 e1 c5 5c fd 90 0f 0b e8 d9 c5 5c fd 90 <0f> 0b e8 d1 c5 5c fd 90 0f 0b e8 c9 c5 5c fd 90 0f 0b e8 c1 c5 5c
RSP: 0018:ffffc9000346ef18 EFLAGS: 00010293
RAX: ffffffff843941b7 RBX: dffffc0000000000 RCX: ffff888023cd5a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff84393d28 R09: ffffffff843804ad
R10: 0000000000000007 R11: ffff888023cd5a00 R12: 1ffff1100eb70101
R13: ffff888071e440a3 R14: 0000000000000000 R15: ffff888071e440a0
FS: 000055556e8b0380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561d03c02678 CR3: 0000000074648000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This report is generated by a bot. It may contain errors.
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https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Edward Adam Davis]

please test kb in cpu_replicas_add_entry

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git cf87f46fd34d

diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index e1800c4119b5..2fc59b8aa32d 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -443,7 +443,7 @@ int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
char *options)
{
char *copied_opts, *copied_opts_start;
- char *opt, *name, *val;
+ char *opt, *name, *val, opts_set = 0;
int ret, id;
struct printbuf err = PRINTBUF;
u64 v;
@@ -498,8 +498,11 @@ int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
goto bad_val;

bch2_opt_set_by_id(opts, id, v);
+ opts_set = 1;
}

+ if (!opts_set)
+ goto bad_opt;
ret = 0;
goto out;

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+734140...@syzkaller.appspotmail.com

Tested on:

commit: cf87f46f Merge tag 'drm-fixes-2024-05-11' of https://g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=152aa96c980000

kernel config: https://syzkaller.appspot.com/x/.config?x=9d7ea7de0cb32587
dashboard link: https://syzkaller.appspot.com/bug?extid=73414091bd382684ee2b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=112bfdd4980000

Note: testing is done by a robot and is best-effort only.

[Edward Adam Davis]

When the input parameter options format is invalid, it will cause the opts object
to not be set correctly.
When a similar situation occurs, it should return -BCH_ERR_option_name and terminate
the mounting action.

Fixes: 03ef80b469d5 ("bcachefs: Ignore unknown mount options")

Reported-and-tested-by: syzbot+734140...@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
fs/bcachefs/opts.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index e1800c4119b5..2fc59b8aa32d 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -443,7 +443,7 @@ int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
char *options)
{
char *copied_opts, *copied_opts_start;
- char *opt, *name, *val;
+ char *opt, *name, *val, opts_set = 0;
int ret, id;
struct printbuf err = PRINTBUF;
u64 v;
@@ -498,8 +498,11 @@ int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
goto bad_val;

bch2_opt_set_by_id(opts, id, v);
+ opts_set = 1;
}

+ if (!opts_set)
+ goto bad_opt;
ret = 0;
goto out;

--
2.43.0