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In-Reply-To: <67ea7949.050a0220.1547ec.0137.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69b32e9b.050a0220.12d28.007d.GAE@google.com> Subject: Forwarded: Re: [syzbot] [ext4?] KASAN: slab-use-after-free Read in ext4_ext_remove_space From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: [syzbot] [ext4?] KASAN: slab-use-after-free Read in ext4_ext_remove_space Author: koike@igalia.com #syz test On 3/31/25 8:15 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: a1c24ab82279 Merge branch 'for-next/el2-enable-feat-pmuv3p.. > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > console output: https://syzkaller.appspot.com/x/log.txt?x=17f953b8580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f6b108de97771157 > dashboard link: https://syzkaller.appspot.com/bug?extid=b73703b873a33d8eb8f6 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > userspace arch: arm64 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/9581dbc26f55/disk-a1c24ab8.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/50aec9ab8b8b/vmlinux-a1c24ab8.xz > kernel image: https://storage.googleapis.com/syzbot-assets/3a018984f8f5/Image-a1c24ab8.gz.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+b73703b873a33d8eb8f6@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: slab-use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2623 [inline] > BUG: KASAN: slab-use-after-free in ext4_ext_remove_space+0x2ce0/0x4058 fs/ext4/extents.c:2961 > Read of size 4 at addr ffff0000dae2c4c8 by task syz.3.297/8071 > > CPU: 0 UID: 0 PID: 8071 Comm: syz.3.297 Not tainted 6.14.0-rc3-syzkaller-ga1c24ab82279 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 > Call trace: > show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C) > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0x198/0x538 mm/kasan/report.c:489 > kasan_report+0xd8/0x138 mm/kasan/report.c:602 > __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380 > ext4_ext_rm_leaf fs/ext4/extents.c:2623 [inline] > ext4_ext_remove_space+0x2ce0/0x4058 fs/ext4/extents.c:2961 > ext4_ext_truncate+0x134/0x1d4 fs/ext4/extents.c:4466 > ext4_truncate+0x9dc/0x10ac fs/ext4/inode.c:4217 > ext4_setattr+0xdc8/0x173c fs/ext4/inode.c:5542 > notify_change+0x9f0/0xca0 fs/attr.c:552 > do_truncate+0x1c0/0x28c fs/open.c:65 > handle_truncate fs/namei.c:3451 [inline] > do_open fs/namei.c:3834 [inline] > path_openat+0x249c/0x2b1c fs/namei.c:3989 > do_filp_open+0x1e8/0x404 fs/namei.c:4016 > do_sys_openat2+0x124/0x1b8 fs/open.c:1428 > do_sys_open fs/open.c:1443 [inline] > __do_sys_openat fs/open.c:1459 [inline] > __se_sys_openat fs/open.c:1454 [inline] > __arm64_sys_openat+0x1f0/0x240 fs/open.c:1454 > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] > invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 > el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 > do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 > el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744 > el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 > > Allocated by task 6060: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x40/0x78 mm/kasan/common.c:68 > kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:562 > unpoison_slab_object mm/kasan/common.c:319 [inline] > __kasan_slab_alloc+0x74/0x8c mm/kasan/common.c:345 > kasan_slab_alloc include/linux/kasan.h:250 [inline] > slab_post_alloc_hook mm/slub.c:4115 [inline] > slab_alloc_node mm/slub.c:4164 [inline] > kmem_cache_alloc_noprof+0x254/0x410 mm/slub.c:4171 > getname_flags+0xcc/0x4b4 fs/namei.c:139 > do_readlinkat+0xbc/0x4d4 fs/stat.c:563 > __do_sys_readlinkat fs/stat.c:595 [inline] > __se_sys_readlinkat fs/stat.c:592 [inline] > __arm64_sys_readlinkat+0x9c/0xb8 fs/stat.c:592 > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] > invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 > el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 > do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 > el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744 > el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 > > Freed by task 6060: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x40/0x78 mm/kasan/common.c:68 > kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:576 > poison_slab_object mm/kasan/common.c:247 [inline] > __kasan_slab_free+0x64/0x8c mm/kasan/common.c:264 > kasan_slab_free include/linux/kasan.h:233 [inline] > slab_free_hook mm/slub.c:2353 [inline] > slab_free mm/slub.c:4609 [inline] > kmem_cache_free+0x198/0x554 mm/slub.c:4711 > putname+0x130/0x184 fs/namei.c:296 > do_readlinkat+0x25c/0x4d4 fs/stat.c:584 > __do_sys_readlinkat fs/stat.c:595 [inline] > __se_sys_readlinkat fs/stat.c:592 [inline] > __arm64_sys_readlinkat+0x9c/0xb8 fs/stat.c:592 > __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] > invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 > el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 > do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 > el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744 > el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762 > el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 > > The buggy address belongs to the object at ffff0000dae2c400 > which belongs to the cache names_cache of size 4096 > The buggy address is located 200 bytes inside of > freed 4096-byte region [ffff0000dae2c400, ffff0000dae2d400) > > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11ae28 > head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 > flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) > page_type: f5(slab) > raw: 05ffc00000000040 ffff0000c18a88c0 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000000070007 00000000f5000000 0000000000000000 > head: 05ffc00000000040 ffff0000c18a88c0 dead000000000122 0000000000000000 > head: 0000000000000000 0000000000070007 00000000f5000000 0000000000000000 > head: 05ffc00000000003 fffffdffc36b8a01 ffffffffffffffff 0000000000000000 > head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff0000dae2c380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff0000dae2c400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff0000dae2c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff0000dae2c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff0000dae2c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup