BUG: KASAN: use-after-free in ext4_search_dir+0xf7/0x1b0 fs/ext4/namei.c:1543
Read of size 1 at addr ffff888125d33d0b by task syz-executor423/303

CPU: 0 PID: 303 Comm: syz-executor423 Not tainted 6.1.90-syzkaller-00122-g7fa70ede91bb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0x158/0x4e0 mm/kasan/report.c:427
 kasan_report+0x13c/0x170 mm/kasan/report.c:531
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348
 ext4_search_dir+0xf7/0x1b0 fs/ext4/namei.c:1543
 ext4_find_inline_entry+0x4b6/0x5e0 fs/ext4/inline.c:1722
 __ext4_find_entry+0x2b0/0x1af0 fs/ext4/namei.c:1616
 ext4_lookup_entry fs/ext4/namei.c:1771 [inline]
 ext4_lookup+0x176/0x740 fs/ext4/namei.c:1839
 __lookup_slow+0x2b9/0x3e0 fs/namei.c:1689
 lookup_slow+0x5a/0x80 fs/namei.c:1706
 walk_component+0x2e7/0x410 fs/namei.c:1997
 lookup_last fs/namei.c:2454 [inline]
 path_lookupat+0x16d/0x450 fs/namei.c:2478
 filename_lookup+0x251/0x600 fs/namei.c:2507
 user_path_at_empty+0x43/0x1a0 fs/namei.c:2906
 user_path_at include/linux/namei.h:57 [inline]
 do_mount fs/namespace.c:3391 [inline]
 __do_sys_mount fs/namespace.c:3602 [inline]
 __se_sys_mount+0x285/0x3b0 fs/namespace.c:3579
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3579
 x64_sys_call+0x49d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1de5638cc9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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:00007ffc445c7338 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f1de5638cc9
RDX: 0000000000000000 RSI: 0000000020002ac0 RDI: 0000000000000000
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc445c7380 R14: 00007ffc445c736c R15: 00007f1de568103b
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004974cc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x125d33
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004974d08 ffffea0004974c88 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x8140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO|__GFP_CMA), pid 321, tgid 321 (syz-executor423), ts 22970928774, free_ts 23037047262
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x213/0x220 mm/page_alloc.c:2590
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2597
 get_page_from_freelist+0x27ea/0x2870 mm/page_alloc.c:4425
 __alloc_pages+0x3a1/0x780 mm/page_alloc.c:5714
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5746
 __folio_alloc_node include/linux/gfp.h:245 [inline]
 folio_alloc include/linux/gfp.h:274 [inline]
 alloc_page_vma include/linux/gfp.h:283 [inline]
 do_anonymous_page mm/memory.c:4245 [inline]
 handle_pte_fault mm/memory.c:5125 [inline]
 __handle_mm_fault mm/memory.c:5269 [inline]
 handle_mm_fault+0x1cf7/0x30e0 mm/memory.c:5409
 do_user_addr_fault arch/x86/mm/fault.c:1354 [inline]
 handle_page_fault arch/x86/mm/fault.c:1497 [inline]
 exc_page_fault+0x3b3/0x700 arch/x86/mm/fault.c:1553
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:570
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1498 [inline]
 free_pcp_prepare mm/page_alloc.c:1572 [inline]
 free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3498
 free_unref_page_list+0xf1/0x7b0 mm/page_alloc.c:3646
 release_pages+0xf7f/0xfe0 mm/swap.c:1063
 free_pages_and_swap_cache+0x8a/0xa0 mm/swap_state.c:315
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu mm/mmu_gather.c:261 [inline]
 tlb_finish_mmu+0x1e0/0x3f0 mm/mmu_gather.c:361
 unmap_region+0x2c1/0x310 mm/mmap.c:2405
 do_mas_align_munmap+0xd05/0x1400 mm/mmap.c:2672
 do_mas_munmap+0x23e/0x2b0 mm/mmap.c:2730
 __vm_munmap+0x263/0x3a0 mm/mmap.c:3020
 __do_sys_munmap mm/mmap.c:3046 [inline]
 __se_sys_munmap mm/mmap.c:3042 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3042
 x64_sys_call+0x75/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888125d33c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888125d33c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888125d33d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff888125d33d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888125d33e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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