syzbot has found a reproducer for the following issue on:

HEAD commit: faf68e3523c2 Merge tag 'kbuild-fixes-v6.1-4' of git://git... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16c3fb9b880000 kernel config: https://syzkaller.appspot.com/x/.config?x=8d01b6e3197974dd dashboard link: https://syzkaller.appspot.com/bug?extid=c6fd14145e2f62ca0784 compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10fa1ce3880000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1092ed73880000

Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3bfa6577f378/disk-faf68e35.raw.... vmlinux: https://storage.googleapis.com/syzbot-assets/7bf0af58cde3/vmlinux-faf68e35.x... kernel image: https://storage.googleapis.com/syzbot-assets/3e15d7d640b0/bzImage-faf68e35.x... mounted in repro: https://storage.googleapis.com/syzbot-assets/e69d0b505238/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c6fd14145e2f62ca0784@syzkaller.appspotmail.com

================================================================== BUG: KASAN: stack-out-of-bounds in gfs2_dump_glock+0x1537/0x1b60 Read of size 8 at addr ffffc9000493fcc0 by task syz-executor301/4070

CPU: 0 PID: 4070 Comm: syz-executor301 Not tainted 6.1.0-rc6-syzkaller-00315-gfaf68e3523c2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:284 print_report+0x107/0x1f0 mm/kasan/report.c:395 kasan_report+0xcd/0x100 mm/kasan/report.c:495 gfs2_dump_glock+0x1537/0x1b60 gfs2_consist_inode_i+0xf3/0x110 fs/gfs2/util.c:465 gfs2_dirent_scan+0x535/0x650 fs/gfs2/dir.c:602 gfs2_dirent_search+0x2ea/0xb10 fs/gfs2/dir.c:850 gfs2_dir_search+0x8c/0x2a0 fs/gfs2/dir.c:1650 gfs2_lookupi+0x465/0x650 fs/gfs2/inode.c:323 __gfs2_lookup+0x8c/0x260 fs/gfs2/inode.c:870 __lookup_slow+0x266/0x3a0 fs/namei.c:1685 lookup_slow+0x53/0x70 fs/namei.c:1702 walk_component+0x2e1/0x410 fs/namei.c:1993 lookup_last fs/namei.c:2450 [inline] path_lookupat+0x17d/0x450 fs/namei.c:2474 filename_lookup+0x274/0x650 fs/namei.c:2503 user_path_at_empty+0x40/0x1a0 fs/namei.c:2876 do_readlinkat+0x10c/0x3d0 fs/stat.c:468 __do_sys_readlink fs/stat.c:501 [inline] __se_sys_readlink fs/stat.c:498 [inline] __x64_sys_readlink+0x7b/0x90 fs/stat.c:498 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fc648229e99 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007fc648189208 EFLAGS: 00000246 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007fc6482c0568 RCX: 00007fc648229e99 RDX: 0000000000000047 RSI: 0000000020000140 RDI: 0000000020000000 RBP: 00007fc6482c0560 R08: 00007fc648189700 R09: 0000000000000000 R10: 00007fc648189700 R11: 0000000000000246 R12: 00007fc6482c056c R13: 00007ffc15b2f1ff R14: 00007fc648189300 R15: 0000000000022000 </TASK>

The buggy address belongs to the virtual mapping at [ffffc90004938000, ffffc90004941000) created by: dup_task_struct+0x8b/0x490 kernel/fork.c:974

The buggy address belongs to the physical page: page:ffffea000073ed00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1cfb4 memcg:ffff8881481da382 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000001ffffffff ffff8881481da382 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 4055, tgid 4055 (syz-executor301), ts 493360110858, free_ts 493203659028 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4291 __alloc_pages+0x259/0x560 mm/page_alloc.c:5558 vm_area_alloc_pages mm/vmalloc.c:2975 [inline] __vmalloc_area_node mm/vmalloc.c:3043 [inline] __vmalloc_node_range+0x8f4/0x1290 mm/vmalloc.c:3213 alloc_thread_stack_node+0x307/0x500 kernel/fork.c:311 dup_task_struct+0x8b/0x490 kernel/fork.c:974 copy_process+0x637/0x4000 kernel/fork.c:2084 kernel_clone+0x21b/0x620 kernel/fork.c:2671 __do_sys_clone kernel/fork.c:2812 [inline] __se_sys_clone kernel/fork.c:2796 [inline] __x64_sys_clone+0x228/0x290 kernel/fork.c:2796 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1459 [inline] free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1509 free_unref_page_prepare mm/page_alloc.c:3387 [inline] free_unref_page_list+0xb4/0x7b0 mm/page_alloc.c:3529 release_pages+0x232a/0x25c0 mm/swap.c:1055 __pagevec_release+0x7d/0xf0 mm/swap.c:1075 pagevec_release include/linux/pagevec.h:71 [inline] folio_batch_release include/linux/pagevec.h:135 [inline] truncate_inode_pages_range+0x472/0x17f0 mm/truncate.c:373 kill_bdev block/bdev.c:76 [inline] blkdev_flush_mapping+0x153/0x2c0 block/bdev.c:662 blkdev_put_whole block/bdev.c:693 [inline] blkdev_put+0x4a5/0x730 block/bdev.c:953 deactivate_locked_super+0xa7/0xf0 fs/super.c:332 cleanup_mnt+0x494/0x520 fs/namespace.c:1186 task_work_run+0x243/0x300 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:171 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:296 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address: ffffc9000493fb80: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 ffffc9000493fc00: 00 f2 f2 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 00

ffffc9000493fc80: 00 00 00 00 00 00 00 00 f3 f3 f3 f3 00 00 00 00

^ ffffc9000493fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffffc9000493fd80: f1 f1 f1 f1 04 f3 f3 f3 00 00 00 00 00 00 00 00 ==================================================================