Message-ID: <000000000000d133670620c640fe@google.com>
Date: Wed, 28 Aug 2024 15:55:23 -0700
From: syzbot <syzbot+46b0888255f68622d309@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, asml.silence@...il.com, axboe@...nel.dk, 
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] KASAN: use-after-free Read in ext4_inlinedir_to_tree

Hello,

syzbot found the following issue on:

HEAD commit:    d2bafcf224f3 Merge tag 'cgroup-for-6.11-rc4-fixes' of git:..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1660edd5980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4fc2afd52fd008bb
dashboard link: https://syzkaller.appspot.com/bug?extid=46b0888255f68622d309
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15d4ae09980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=158d6609980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7569f02310fb/disk-d2bafcf2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e30fee7b6c1d/vmlinux-d2bafcf2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2ffddebac153/bzImage-d2bafcf2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e4fb4afad539/mount_0.gz

The issue was bisected to:

commit e5598d6ae62626d261b046a2f19347c38681ff51
Author: Pavel Begunkov <asml.silence@...il.com>
Date:   Thu Aug 24 22:53:31 2023 +0000

    io_uring: compact SQ/CQ heads/tails

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13308233980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=10b08233980000
console output: https://syzkaller.appspot.com/x/log.txt?x=17308233980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+46b0888255f68622d309@...kaller.appspotmail.com
Fixes: e5598d6ae626 ("io_uring: compact SQ/CQ heads/tails")

EXT4-fs error (device loop0): htree_dirblock_to_tree:1112: inode #2: block 21: comm syz-executor129: bad entry in directory: directory entry overrun - offset=1004, inode=0, rec_len=1000, size=1024 fake=0
==================================================================
BUG: KASAN: use-after-free in ext4_read_inline_data fs/ext4/inline.c:209 [inline]
BUG: KASAN: use-after-free in ext4_inlinedir_to_tree+0x57a/0x11d0 fs/ext4/inline.c:1365
Read of size 324 at addr ffff8880717c5c05 by task syz-executor129/5213

CPU: 0 UID: 0 PID: 5213 Comm: syz-executor129 Not tainted 6.11.0-rc4-syzkaller-00255-gd2bafcf224f3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 ext4_read_inline_data fs/ext4/inline.c:209 [inline]
 ext4_inlinedir_to_tree+0x57a/0x11d0 fs/ext4/inline.c:1365
 ext4_htree_fill_tree+0x5d8/0x1400 fs/ext4/namei.c:1211
 ext4_dx_readdir fs/ext4/dir.c:597 [inline]
 ext4_readdir+0x2b1c/0x3500 fs/ext4/dir.c:142
 iterate_dir+0x57a/0x810 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:407 [inline]
 __se_sys_getdents64+0x20d/0x4f0 fs/readdir.c:392
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcb146ca613
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 42 23 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:00007fffaa54eac8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555567e83770 RCX: 00007fcb146ca613
RDX: 0000000000008000 RSI: 0000555567e83770 RDI: 0000000000000005
RBP: 0000555567e83744 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: ffffffffffffffb8
R13: 0000000000000016 R14: 0000555567e83740 R15: 00007fffaa551e30
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x5615451c4 pfn:0x717c5
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 00000005615451c4 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5174, tgid 5174 (sftp-server), ts 48575534501, free_ts 49882330156
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2263
 folio_alloc_mpol_noprof mm/mempolicy.c:2281 [inline]
 vma_alloc_folio_noprof+0x12e/0x230 mm/mempolicy.c:2312
 folio_prealloc+0x31/0x170
 alloc_anon_folio mm/memory.c:4498 [inline]
 do_anonymous_page mm/memory.c:4555 [inline]
 do_pte_missing mm/memory.c:3945 [inline]
 handle_pte_fault+0x255e/0x6fc0 mm/memory.c:5521
 __handle_mm_fault mm/memory.c:5664 [inline]
 handle_mm_fault+0xf70/0x1880 mm/memory.c:5832
 do_user_addr_fault arch/x86/mm/fault.c:1338 [inline]
 handle_page_fault arch/x86/mm/fault.c:1481 [inline]
 exc_page_fault+0x459/0x8c0 arch/x86/mm/fault.c:1539
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 5174 tgid 5174 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_folios+0x100f/0x1ac0 mm/page_alloc.c:2660
 folios_put_refs+0x76e/0x860 mm/swap.c:1039
 free_pages_and_swap_cache+0x2ea/0x690 mm/swap_state.c:332
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
 tlb_flush_mmu+0x3a3/0x680 mm/mmu_gather.c:373
 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:465
 exit_mmap+0x44f/0xc80 mm/mmap.c:3425
 __mmput+0x115/0x380 kernel/fork.c:1345
 exit_mm+0x220/0x310 kernel/exit.c:571
 do_exit+0x9b2/0x27f0 kernel/exit.c:869
 do_group_exit+0x207/0x2c0 kernel/exit.c:1031
 __do_sys_exit_group kernel/exit.c:1042 [inline]
 __se_sys_exit_group kernel/exit.c:1040 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880717c5b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880717c5b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880717c5c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8880717c5c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880717c5d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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