[syzbot] [xfs?] KMSAN: uninit-value in xfs_dialloc_ag_inobt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8560697b23dc Merge tag '6.15-rc2-smb3-client-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d3dfe4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a27b81e0cf56c60b
dashboard link: https://syzkaller.appspot.com/bug?extid=b4a84825ea149bb99bfc
compiler: Debian clang version 15.0.6, Debian LLD 15.0.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/03806cf4a3af/disk-8560697b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6d86507d5b30/vmlinux-8560697b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f5f2020007a8/bzImage-8560697b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b4a848...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in xfs_dialloc_ag_inobt+0x99b/0x2550 fs/xfs/libxfs/xfs_ialloc.c:1173
xfs_dialloc_ag_inobt+0x99b/0x2550 fs/xfs/libxfs/xfs_ialloc.c:1173
xfs_dialloc_ag fs/xfs/libxfs/xfs_ialloc.c:1585 [inline]
xfs_dialloc_try_ag fs/xfs/libxfs/xfs_ialloc.c:1835 [inline]
xfs_dialloc+0x14c4/0x3470 fs/xfs/libxfs/xfs_ialloc.c:1945
xfs_create_tmpfile+0x496/0x12c0 fs/xfs/xfs_inode.c:827
xfs_generic_create+0x65c/0x1610 fs/xfs/xfs_iops.c:227
xfs_vn_tmpfile+0x6b/0x140 fs/xfs/xfs_iops.c:1194
vfs_tmpfile+0x5e4/0xe40 fs/namei.c:3896
do_tmpfile+0x19d/0x460 fs/namei.c:3961
path_openat+0x4837/0x6280 fs/namei.c:3995
do_filp_open+0x26b/0x610 fs/namei.c:4031
io_openat2+0x5d5/0xa50 io_uring/openclose.c:140
io_openat+0x35/0x40 io_uring/openclose.c:177
__io_issue_sqe io_uring/io_uring.c:1734 [inline]
io_issue_sqe+0x394/0x1de0 io_uring/io_uring.c:1753
io_wq_submit_work+0xaf8/0xde0 io_uring/io_uring.c:1868
io_worker_handle_work+0xc4d/0x2090 io_uring/io-wq.c:615
io_wq_worker+0x403/0x1470 io_uring/io-wq.c:669
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
xfs_dialloc_ag_inobt+0x1cc1/0x2550 fs/xfs/libxfs/xfs_ialloc.c:1227
xfs_dialloc_ag fs/xfs/libxfs/xfs_ialloc.c:1585 [inline]
xfs_dialloc_try_ag fs/xfs/libxfs/xfs_ialloc.c:1835 [inline]
xfs_dialloc+0x14c4/0x3470 fs/xfs/libxfs/xfs_ialloc.c:1945
xfs_create_tmpfile+0x496/0x12c0 fs/xfs/xfs_inode.c:827
xfs_generic_create+0x65c/0x1610 fs/xfs/xfs_iops.c:227
xfs_vn_tmpfile+0x6b/0x140 fs/xfs/xfs_iops.c:1194
vfs_tmpfile+0x5e4/0xe40 fs/namei.c:3896
do_tmpfile+0x19d/0x460 fs/namei.c:3961
path_openat+0x4837/0x6280 fs/namei.c:3995
do_filp_open+0x26b/0x610 fs/namei.c:4031
io_openat2+0x5d5/0xa50 io_uring/openclose.c:140
io_openat+0x35/0x40 io_uring/openclose.c:177
__io_issue_sqe io_uring/io_uring.c:1734 [inline]
io_issue_sqe+0x394/0x1de0 io_uring/io_uring.c:1753
io_wq_submit_work+0xaf8/0xde0 io_uring/io_uring.c:1868
io_worker_handle_work+0xc4d/0x2090 io_uring/io-wq.c:615
io_wq_worker+0x403/0x1470 io_uring/io-wq.c:669
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 trec created at:
xfs_dialloc_ag_inobt+0x139/0x2550 fs/xfs/libxfs/xfs_ialloc.c:1101
xfs_dialloc_ag fs/xfs/libxfs/xfs_ialloc.c:1585 [inline]
xfs_dialloc_try_ag fs/xfs/libxfs/xfs_ialloc.c:1835 [inline]
xfs_dialloc+0x14c4/0x3470 fs/xfs/libxfs/xfs_ialloc.c:1945

CPU: 1 UID: 0 PID: 7854 Comm: iou-wrk-7829 Not tainted 6.15.0-rc2-syzkaller-00404-g8560697b23dc #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
=====================================================


---
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[Arnaud Lecomte]

#syz test

--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -1182,6 +1182,8 @@ xfs_dialloc_ag_inobt(
if (error)
goto error1;
} else {
+ pag->pagl_leftrec = NULLAGINO;
+ pag->pagl_rightrec = NULLAGINO;
/* search left with tcur, back up 1 record */
error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
if (error)

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.