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KASAN: use-after-free Read in ext4_read_inline_dir (2)

Status: upstream: reported C repro on 2024/12/31 16:48
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+ac63730e8e5e21567ff1@syzkaller.appspotmail.com
First crash: 14d, last: 14h30m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/01/04 lts (merge base) b67dc5c9ade9 C [report] KASAN: out-of-bounds Read in ext4_read_inline_dir
2025/01/04 upstream (ToT) 63676eefb7a0 C [report] KASAN: use-after-free Read in ext4_read_inline_data
▶ ▼ Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in ext4_read_inline_dir 1 169d 169d 0/2 auto-obsoleted due to no activity on 2024/10/28 03:11
android-5-15 KASAN: use-after-free Read in ext4_read_inline_dir origin:upstream C 3 7d18h 7d19h 0/2 upstream: reported C repro on 2025/01/07 14:17
upstream KASAN: slab-out-of-bounds Read in ext4_read_inline_dir ext4 C done 79 43d 171d 0/28 upstream: reported C repro on 2024/07/28 07:54
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2025/01/14 18:27 27m retest repro android14-6.1 report log
2025/01/14 18:27 7m retest repro android14-6.1 report log
2025/01/14 18:27 6m retest repro android14-6.1 report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ext4_read_inline_data fs/ext4/inline.c:210 [inline]
BUG: KASAN: use-after-free in ext4_read_inline_dir+0x48c/0xf60 fs/ext4/inline.c:1512
Read of size 68 at addr ffff888127253d05 by task syz-executor349/300

CPU: 1 PID: 300 Comm: syz-executor349 Not tainted 6.1.118-syzkaller-00078-ge2b9748880b9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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
 kasan_check_range+0x294/0x2a0 mm/kasan/generic.c:189
 memcpy+0x2d/0x70 mm/kasan/shadow.c:65
 ext4_read_inline_data fs/ext4/inline.c:210 [inline]
 ext4_read_inline_dir+0x48c/0xf60 fs/ext4/inline.c:1512
 ext4_readdir+0x3d1/0x3860 fs/ext4/dir.c:158
 iterate_dir+0x265/0x600
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0x1c1/0x460 fs/readdir.c:354
 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354
 x64_sys_call+0x5ae/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:218
 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: 0033:0x7ff4c876c573
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 62 49 fb ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 b8 ff ff ff f7 d8
RSP: 002b:00007fffa1dca1a8 EFLAGS: 00000293
 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555579524870 RCX: 00007ff4c876c573
RDX: 0000000000008000 RSI: 0000555579524870 RDI: 0000000000000005
RBP: 0000555579524844 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: ffffffffffffffb8
R13: 0000000000000016 R14: 0000555579524840 R15: 00007fffa1dcd510
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00049c94c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x127253
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea00049c9508 ffffea00049cf048 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 235, tgid 235 (sshd), ts 16377262532, free_ts 16396421232
 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+0x2f41/0x2fc0 mm/page_alloc.c:4462
 __alloc_pages+0x234/0x610 mm/page_alloc.c:5759
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5791
 __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:4269 [inline]
 handle_pte_fault mm/memory.c:5155 [inline]
 __handle_mm_fault mm/memory.c:5299 [inline]
 handle_mm_fault+0x1cf7/0x30e0 mm/memory.c:5439
 do_user_addr_fault arch/x86/mm/fault.c:1323 [inline]
 handle_page_fault arch/x86/mm/fault.c:1466 [inline]
 exc_page_fault+0x3b3/0x6d0 arch/x86/mm/fault.c:1522
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
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:3511
 free_unref_page_list+0xf1/0x7b0 mm/page_alloc.c:3659
 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:2403
 do_mas_align_munmap+0xd05/0x1400 mm/mmap.c:2670
 do_mas_munmap+0x23e/0x2b0 mm/mmap.c:2728
 __vm_munmap+0x263/0x3a0 mm/mmap.c:3018
 __do_sys_munmap mm/mmap.c:3044 [inline]
 __se_sys_munmap mm/mmap.c:3040 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3040
 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:
 ffff888127253c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888127253c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888127253d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888127253d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888127253e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): empty_inline_dir:1877: inode #12: block 5: comm syz-executor349: bad entry in directory: rec_len % 4 != 0 - offset=4, inode=1633771873, rec_len=24929, size=60 fake=0
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): empty_inline_dir:1877: inode #12: block 5: comm syz-executor349: bad entry in directory: rec_len % 4 != 0 - offset=4, inode=1633771873, rec_len=24929, size=60 fake=0
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): ext4_read_inline_dir:1593: inode #12: block 5: comm syz-executor349: path /root/syzkaller.cUku6Y/0/file0/file0: bad entry in directory: rec_len % 4 != 0 - offset=24, inode=1633771873, rec_len=24929, size=148 fake=0
EXT4-fs error (device loop3): empty_inline_dir:1877: inode #12: block 5: comm syz-executor349: bad entry in directory: rec_len % 4 != 0 - offset=4, inode=1633771873, rec_len=24929, size=60 fake=0
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60
EXT4-fs warning (device loop3): empty_inline_dir:1884: bad inline directory (dir #12) - inode 1633771873, rec_len 24929, name_len 97inline size 60

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/31 17:40 android14-6.1 e2b9748880b9 d3ccff63 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: use-after-free Read in ext4_read_inline_dir
2024/12/31 16:46 android14-6.1 e2b9748880b9 d3ccff63 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: use-after-free Read in ext4_read_inline_dir
2024/12/31 17:09 android14-6.1 e2b9748880b9 d3ccff63 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-6-1 KASAN: out-of-bounds Read in ext4_read_inline_dir
* Struck through repros no longer work on HEAD.