[syzbot] [ext4?] KMSAN: uninit-value in mb_find_extent

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    e919e2b1bc1c Revert "kmsan: disallow CONFIG_KMSAN with CON..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1199a6ea480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b63e082c4fda2e77
dashboard link: https://syzkaller.appspot.com/bug?extid=b6451edec162751aba49
compiler:       clang version 15.0.0 (https://github.com/llvm/llvm-project.git 610139d2d9ce6746b3c617fb3e2f7886272d26ff), GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5676c9771994/disk-e919e2b1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7f53a1472ca4/vmlinux-e919e2b1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eb021c0a44de/bzImage-e919e2b1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b6451edec162751aba49@xxxxxxxxxxxxxxxxxxxxxxxxx

R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
---[ end trace 0000000000000000 ]---
=====================================================
BUG: KMSAN: uninit-value in mb_find_extent+0x1603/0x1640 fs/ext4/mballoc.c:1870
 mb_find_extent+0x1603/0x1640 fs/ext4/mballoc.c:1870
 ext4_mb_complex_scan_group+0x456/0x1760 fs/ext4/mballoc.c:2307
 ext4_mb_regular_allocator+0x2e60/0x5c30 fs/ext4/mballoc.c:2735
 ext4_mb_new_blocks+0x1708/0x2fe0 fs/ext4/mballoc.c:5605
 ext4_ext_map_blocks+0x2fb5/0x5a60 fs/ext4/extents.c:4286
 ext4_map_blocks+0x13ae/0x2d70 fs/ext4/inode.c:651
 ext4_getblk+0x228/0xd10 fs/ext4/inode.c:864
 ext4_bread+0x46/0x370 fs/ext4/inode.c:920
 ext4_quota_write+0x2f5/0x9c0 fs/ext4/super.c:7105
 write_blk fs/quota/quota_tree.c:64 [inline]
 get_free_dqblk+0x46e/0x910 fs/quota/quota_tree.c:130
 do_insert_tree+0x300/0x3190 fs/quota/quota_tree.c:340
 do_insert_tree+0xd42/0x3190 fs/quota/quota_tree.c:375
 do_insert_tree+0xd42/0x3190 fs/quota/quota_tree.c:375
 dq_insert_tree fs/quota/quota_tree.c:401 [inline]
 qtree_write_dquot+0x616/0x730 fs/quota/quota_tree.c:420
 v2_write_dquot+0x14e/0x220 fs/quota/quota_v2.c:358
 dquot_acquire+0x450/0x700 fs/quota/dquot.c:444
 ext4_acquire_dquot+0x44d/0x540 fs/ext4/super.c:6740
 dqget+0x12db/0x1a90 fs/quota/dquot.c:914
 __dquot_initialize+0x67a/0x1730 fs/quota/dquot.c:1492
 dquot_initialize+0x2e/0x40 fs/quota/dquot.c:1550
 ext4_process_orphan+0x56/0x4f0 fs/ext4/orphan.c:329
 ext4_orphan_cleanup+0x1160/0x1c60 fs/ext4/orphan.c:474
 __ext4_fill_super fs/ext4/super.c:5516 [inline]
 ext4_fill_super+0xd0dc/0xd7f0 fs/ext4/super.c:5644
 get_tree_bdev+0x8a3/0xd30 fs/super.c:1282
 ext4_get_tree+0x30/0x40 fs/ext4/super.c:5675
 vfs_get_tree+0xa1/0x500 fs/super.c:1489
 do_new_mount+0x694/0x1580 fs/namespace.c:3145
 path_mount+0x71a/0x1eb0 fs/namespace.c:3475
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount+0x734/0x840 fs/namespace.c:3674
 __ia32_sys_mount+0xdf/0x140 fs/namespace.c:3674
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
 entry_SYSENTER_compat_after_hwframe+0x70/0x82

Local variable ex created at:
 ext4_mb_complex_scan_group+0xa3/0x1760 fs/ext4/mballoc.c:2279
 ext4_mb_regular_allocator+0x2e60/0x5c30 fs/ext4/mballoc.c:2735

CPU: 1 PID: 6514 Comm: syz-executor.3 Tainted: G        W          6.2.0-rc3-syzkaller-79343-ge919e2b1bc1c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
=====================================================


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