From: syzbot <syzbot+3ee481e21fd75e14c397@syzkaller.appspotmail.com>
To: kartikey406@gmail.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [ext4?] KASAN: slab-out-of-bounds Read in ext4_search_dir
Date: Wed, 01 Oct 2025 23:49:03 -0700 [thread overview]
Message-ID: <68de205f.050a0220.1696c6.002e.GAE@google.com> (raw)
In-Reply-To: <20251002062804.2167179-1-kartikey406@gmail.com>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in ext4_search_dir
==================================================================
BUG: KASAN: use-after-free in ext4_search_dir+0xf1/0x1b0 fs/ext4/namei.c:1469
Read of size 1 at addr ffff88804907506b by task syz.0.23/5978
CPU: 0 UID: 0 PID: 5978 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
ext4_search_dir+0xf1/0x1b0 fs/ext4/namei.c:1469
ext4_find_inline_entry+0x492/0x5f0 fs/ext4/inline.c:1621
__ext4_find_entry+0x2fd/0x1f20 fs/ext4/namei.c:1542
ext4_lookup_entry fs/ext4/namei.c:1703 [inline]
ext4_lookup+0x13d/0x6c0 fs/ext4/namei.c:1771
lookup_open fs/namei.c:3774 [inline]
open_last_lookups fs/namei.c:3895 [inline]
path_openat+0x10fe/0x3830 fs/namei.c:4131
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1435
do_sys_open fs/open.c:1450 [inline]
__do_sys_openat fs/open.c:1466 [inline]
__se_sys_openat fs/open.c:1461 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1461
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f999878eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9997ddd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f99989e6090 RCX: 00007f999878eec9
RDX: 0000000000000042 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f9998811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f99989e6128 R14: 00007f99989e6090 R15: 00007fffca9efab8
</TASK>
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xc002573 pfn:0x49075
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 000000000c002573 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_ZERO|__GFP_COMP), pid 5609, tgid 5609 (syz-execprog), ts 124343619274, free_ts 141401086768
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
prep_new_page mm/page_alloc.c:1859 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
folio_alloc_mpol_noprof mm/mempolicy.c:2435 [inline]
vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2470
folio_prealloc+0x30/0x180 mm/memory.c:-1
alloc_anon_folio mm/memory.c:4997 [inline]
do_anonymous_page mm/memory.c:5054 [inline]
do_pte_missing mm/memory.c:4232 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault+0x2ab9/0x5440 mm/memory.c:6195
handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 78 tgid 78 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1395 [inline]
free_unref_folios+0xdbd/0x1520 mm/page_alloc.c:2952
shrink_folio_list+0x2977/0x4cd0 mm/vmscan.c:1568
evict_folios+0x471e/0x57c0 mm/vmscan.c:4744
try_to_shrink_lruvec+0x8a3/0xb50 mm/vmscan.c:4907
shrink_one+0x21b/0x7c0 mm/vmscan.c:4952
shrink_many mm/vmscan.c:5015 [inline]
lru_gen_shrink_node mm/vmscan.c:5093 [inline]
shrink_node+0x314e/0x3760 mm/vmscan.c:6078
kswapd_shrink_node mm/vmscan.c:6938 [inline]
balance_pgdat mm/vmscan.c:7121 [inline]
kswapd+0x147c/0x2830 mm/vmscan.c:7386
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Memory state around the buggy address:
ffff888049074f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888049074f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888049075000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888049075080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888049075100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Tested on:
commit: 7f707257 Merge tag 'kbuild-6.18-1' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15a92092580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c0364a9e4a291ab2
dashboard link: https://syzkaller.appspot.com/bug?extid=3ee481e21fd75e14c397
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=15786334580000
next parent reply other threads:[~2025-10-02 6:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20251002062804.2167179-1-kartikey406@gmail.com>
2025-10-02 6:49 ` syzbot [this message]
[not found] <aRZ0EwX9Ajg38Sei@rpthibeault-XPS-13-9305>
2025-11-14 0:34 ` [syzbot] [ext4?] KASAN: slab-out-of-bounds Read in ext4_search_dir syzbot
[not found] <aRZbvQgQgxVbfgow@rpthibeault-XPS-13-9305>
2025-11-13 22:48 ` syzbot
[not found] <aQ-D6qQkBA6XUgyD@rpthibeault-XPS-13-9305>
2025-11-08 18:16 ` syzbot
[not found] <aQ7WfQOMTIDiPBin@rpthibeault-XPS-13-9305>
2025-11-08 5:55 ` syzbot
[not found] <20251003090932.2559979-1-kartikey406@gmail.com>
2025-10-03 9:30 ` syzbot
[not found] <20251003083604.2556017-1-kartikey406@gmail.com>
2025-10-03 8:57 ` syzbot
[not found] <20251003081442.2555454-1-kartikey406@gmail.com>
2025-10-03 8:35 ` syzbot
[not found] <20251003061658.2515919-1-kartikey406@gmail.com>
2025-10-03 6:38 ` syzbot
[not found] <20251003040153.2411696-1-kartikey406@gmail.com>
2025-10-03 4:23 ` syzbot
[not found] <20251003031625.2411015-1-kartikey406@gmail.com>
2025-10-03 3:43 ` syzbot
[not found] <20251003030202.2409492-1-kartikey406@gmail.com>
2025-10-03 3:23 ` syzbot
[not found] <20251003020223.2408483-1-kartikey406@gmail.com>
2025-10-03 2:23 ` syzbot
[not found] <20251003014049.2407777-1-kartikey406@gmail.com>
2025-10-03 2:02 ` syzbot
[not found] <20251003010657.2402278-1-kartikey406@gmail.com>
2025-10-03 1:28 ` syzbot
[not found] <20251003002303.2398961-1-kartikey406@gmail.com>
2025-10-03 0:44 ` syzbot
[not found] <20251002235337.2398242-1-kartikey406@gmail.com>
2025-10-03 0:16 ` syzbot
[not found] <20251002225742.2395560-1-kartikey406@gmail.com>
2025-10-02 23:34 ` syzbot
[not found] <20251002100108.2390216-1-kartikey406@gmail.com>
2025-10-02 10:32 ` syzbot
[not found] <20251002093807.2387597-1-kartikey406@gmail.com>
2025-10-02 9:48 ` syzbot
[not found] <20251002061821.2163863-1-kartikey406@gmail.com>
2025-10-02 6:26 ` syzbot
[not found] <20251002050906.2082433-1-kartikey406@gmail.com>
2025-10-02 5:30 ` syzbot
2025-10-02 0:10 syzbot
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