[syzbot] [bcachefs?] KMSAN: uninit-value in bch2_bucket_alloc_trans

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ceb8bf2ceaa7 module: Convert default symbol namespace to s..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f560f8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96ee18b6611821ab
dashboard link: https://syzkaller.appspot.com/bug?extid=c761143a86b1640bc485
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2cdefe23324a/disk-ceb8bf2c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/db82aad0847e/vmlinux-ceb8bf2c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/616c479edfca/bzImage-ceb8bf2c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c76114...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
BUG: KMSAN: uninit-value in try_alloc_bucket fs/bcachefs/alloc_foreground.c:314 [inline]
BUG: KMSAN: uninit-value in bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:525 [inline]
BUG: KMSAN: uninit-value in bch2_bucket_alloc_trans+0x2533/0x3fb0 fs/bcachefs/alloc_foreground.c:648
bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
try_alloc_bucket fs/bcachefs/alloc_foreground.c:314 [inline]
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:525 [inline]
bch2_bucket_alloc_trans+0x2533/0x3fb0 fs/bcachefs/alloc_foreground.c:648
bch2_bucket_alloc_set_trans+0x959/0x1650 fs/bcachefs/alloc_foreground.c:808
__open_bucket_add_buckets+0x1dec/0x3070 fs/bcachefs/alloc_foreground.c:1057
open_bucket_add_buckets+0x328/0x530 fs/bcachefs/alloc_foreground.c:1101
bch2_alloc_sectors_start_trans+0x1833/0x32b0
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:339 [inline]
bch2_btree_reserve_get+0x9d6/0x2290 fs/bcachefs/btree_update_interior.c:549
bch2_btree_update_start+0x1af9/0x2d60 fs/bcachefs/btree_update_interior.c:1247
bch2_btree_node_rewrite+0x1da/0x1930 fs/bcachefs/btree_update_interior.c:2148
async_btree_node_rewrite_trans fs/bcachefs/btree_update_interior.c:2236 [inline]
async_btree_node_rewrite_work+0x485/0x1710 fs/bcachefs/btree_update_interior.c:2249
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
kthread+0x3e2/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was stored to memory at:
memcpy_u64s_small fs/bcachefs/util.h:393 [inline]
bkey_reassemble fs/bcachefs/bkey.h:513 [inline]
btree_key_cache_create fs/bcachefs/btree_key_cache.c:259 [inline]
btree_key_cache_fill+0x13da/0x3d60 fs/bcachefs/btree_key_cache.c:309
bch2_btree_path_traverse_cached+0x988/0xe20 fs/bcachefs/btree_key_cache.c:361
bch2_btree_path_traverse_one+0x749/0x47b0 fs/bcachefs/btree_iter.c:1159
bch2_btree_path_traverse fs/bcachefs/btree_iter.h:247 [inline]
bch2_btree_iter_peek_slot+0x10b7/0x3950 fs/bcachefs/btree_iter.c:2629
__bch2_bkey_get_iter fs/bcachefs/btree_iter.h:575 [inline]
bch2_bkey_get_iter fs/bcachefs/btree_iter.h:589 [inline]
try_alloc_bucket fs/bcachefs/alloc_foreground.c:305 [inline]
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:525 [inline]
bch2_bucket_alloc_trans+0x1bd5/0x3fb0 fs/bcachefs/alloc_foreground.c:648
bch2_bucket_alloc_set_trans+0x959/0x1650 fs/bcachefs/alloc_foreground.c:808
__open_bucket_add_buckets+0x1dec/0x3070 fs/bcachefs/alloc_foreground.c:1057
open_bucket_add_buckets+0x328/0x530 fs/bcachefs/alloc_foreground.c:1101
bch2_alloc_sectors_start_trans+0x1833/0x32b0
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:339 [inline]
bch2_btree_reserve_get+0x9d6/0x2290 fs/bcachefs/btree_update_interior.c:549
bch2_btree_update_start+0x1af9/0x2d60 fs/bcachefs/btree_update_interior.c:1247
bch2_btree_node_rewrite+0x1da/0x1930 fs/bcachefs/btree_update_interior.c:2148
async_btree_node_rewrite_trans fs/bcachefs/btree_update_interior.c:2236 [inline]
async_btree_node_rewrite_work+0x485/0x1710 fs/bcachefs/btree_update_interior.c:2249
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
kthread+0x3e2/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
___kmalloc_large_node+0x22c/0x370 mm/slub.c:4238
__kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4255
__do_kmalloc_node mm/slub.c:4271 [inline]
__kmalloc_node_noprof+0xc96/0x1250 mm/slub.c:4289
__kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:650
btree_node_data_alloc fs/bcachefs/btree_cache.c:153 [inline]
__bch2_btree_node_mem_alloc+0x2be/0xa80 fs/bcachefs/btree_cache.c:198
bch2_fs_btree_cache_init+0x4e4/0xb50 fs/bcachefs/btree_cache.c:653
bch2_fs_alloc fs/bcachefs/super.c:917 [inline]
bch2_fs_open+0x4d3a/0x5b40 fs/bcachefs/super.c:2065
bch2_fs_get_tree+0x983/0x22d0 fs/bcachefs/fs.c:2157
vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
do_new_mount+0x71f/0x15e0 fs/namespace.c:3507
path_mount+0x742/0x1f10 fs/namespace.c:3834
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x722/0x810 fs/namespace.c:4034
__ia32_sys_mount+0xe3/0x150 fs/namespace.c:4034
ia32_sys_call+0x260e/0x4180 arch/x86/include/generated/asm/syscalls_32.h:22
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:386
do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 1 UID: 0 PID: 4195 Comm: kworker/u8:25 Not tainted 6.13.0-rc1-syzkaller-00005-gceb8bf2ceaa7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: btree_node_rewrite async_btree_node_rewrite_work
=====================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 2df0c02dab82 x86 boot build: make git ignore stale 'tools'..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=135c6a4c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=afd286fb06ecc311

dashboard link: https://syzkaller.appspot.com/bug?extid=c761143a86b1640bc485
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=10355804580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16c86198580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4df46ef3da39/disk-2df0c02d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7585a408245b/vmlinux-2df0c02d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f16d3f20d29/bzImage-2df0c02d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e2708f9fb487/mount_5.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c76114...@syzkaller.appspotmail.com

fragmentation 0
bp_start 8
incorrectly set at freespace:0:31:0 (free 0, genbits 0 should be 0), fixing
=====================================================
BUG: KMSAN: uninit-value in try_alloc_bucket fs/bcachefs/alloc_foreground.c:297 [inline]
BUG: KMSAN: uninit-value in bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:442 [inline]
BUG: KMSAN: uninit-value in bch2_bucket_alloc_trans+0x2191/0x3280 fs/bcachefs/alloc_foreground.c:574
try_alloc_bucket fs/bcachefs/alloc_foreground.c:297 [inline]
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:442 [inline]
bch2_bucket_alloc_trans+0x2191/0x3280 fs/bcachefs/alloc_foreground.c:574
bch2_bucket_alloc_set_trans+0x935/0x1620 fs/bcachefs/alloc_foreground.c:730
__open_bucket_add_buckets+0x1e98/0x3130 fs/bcachefs/alloc_foreground.c:973
open_bucket_add_buckets+0x32b/0x530 fs/bcachefs/alloc_foreground.c:1017
bch2_alloc_sectors_start_trans+0x1839/0x32d0
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:322 [inline]
bch2_btree_reserve_get+0x9eb/0x22b0 fs/bcachefs/btree_update_interior.c:532
bch2_btree_update_start+0x22b8/0x2ec0 fs/bcachefs/btree_update_interior.c:1232
bch2_btree_node_rewrite+0x1da/0x1af0 fs/bcachefs/btree_update_interior.c:2144
async_btree_node_rewrite_trans fs/bcachefs/btree_update_interior.c:2217 [inline]
async_btree_node_rewrite_work+0x74c/0x1aa0 fs/bcachefs/btree_update_interior.c:2253
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xc1d/0x1e80 kernel/workqueue.c:3319
worker_thread+0xea7/0x14f0 kernel/workqueue.c:3400
kthread+0x6b9/0xef0 kernel/kthread.c:464
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Local variable gen.i.i created at:
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:442 [inline]
bch2_bucket_alloc_trans+0x1fb2/0x3280 fs/bcachefs/alloc_foreground.c:574
bch2_bucket_alloc_set_trans+0x935/0x1620 fs/bcachefs/alloc_foreground.c:730

CPU: 1 UID: 0 PID: 4283 Comm: kworker/u8:21 Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025

Workqueue: btree_node_rewrite async_btree_node_rewrite_work
=====================================================


---

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#syz fix bcachefs: Disable asm memcpys when kmsan enabled