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List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6602:3424:b0:887:6ce4:8e07 with SMTP id ca18e2360f4ac-937ad4ae9b4mr927994339f.9.1759387743500; Wed, 01 Oct 2025 23:49:03 -0700 (PDT) Date: Wed, 01 Oct 2025 23:49:03 -0700 In-Reply-To: <20251002062804.2167179-1-kartikey406@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68de205f.050a0220.1696c6.002e.GAE@google.com> Subject: Re: [syzbot] [ext4?] KASAN: slab-out-of-bounds Read in ext4_search_dir From: syzbot To: kartikey406@gmail.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" 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: 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 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