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AHgh+RpTChYoWxpOftzYhAlB3ELNQnHVs/FP+8FOARyXburt6peEQZfH2iuG5UeISVW6y+DI/6QxbXZPashq@vger.kernel.org X-Gm-Message-State: AOJu0YzSODrEWSN8PjwHVU92TOzxMTGofEORVh0sj4n55YUX2s2NhbIi atiIC/v5/cGzK0DZHLknvQLugLSpi0ijBaWldpDEcb4nIm+9QcNVjKCCKJbW5oss+r09EppC4km xnDTq+bKBAVyY93JWU+jJKF/z+0ocg/sOqjL37LqsQFgZ72KEADX11Lbtm+s= Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:308b:b0:6ae:4131:98c6 with SMTP id 006d021491bc7-6b041ee0bb8mr6842764eaf.2.1786302764212; Sun, 09 Aug 2026 12:12:44 -0700 (PDT) Date: Sun, 09 Aug 2026 12:12:44 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a78d12c.01d0871a.3a0d52.008f.GAE@google.com> Subject: [syzbot] [bcache?] [ext4?] KASAN: use-after-free Read in register_bcache From: syzbot To: colyli@fnnas.com, colyli@fygo.io, kent.overstreet@linux.dev, linux-bcache@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: ba5cc80fd326 Merge branch 'for-next/core' into for-kernelci 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=17767fb9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=ccf4bea59f67007 dashboard link: https://syzkaller.appspot.com/bug?extid=cb5b32abe226710cdd8a compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10f67fb9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14cd8149580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/959ad5f4e730/disk-ba5cc80f.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0787d25f251e/vmlinux-ba5cc80f.xz kernel image: https://storage.googleapis.com/syzbot-assets/2e85c36fabac/Image-ba5cc80f.gz.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/130fa1cc1a68/mount_0.gz fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=111f8079580000) IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+cb5b32abe226710cdd8a@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in crc64_be_generic lib/crc/crc64-main.c:47 [inline] BUG: KASAN: use-after-free in crc64_be+0xb8/0xe8 lib/crc/crc64-main.c:68 Read of size 1 at addr ffff0000dd543000 by task syz.0.33/4986 CPU: 1 UID: 0 PID: 4986 Comm: syz.0.33 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xb0/0x238 mm/kasan/report.c:378 print_report+0x68/0x84 mm/kasan/report.c:482 kasan_report+0x8c/0xc4 mm/kasan/report.c:595 __asan_report_load1_noabort+0x20/0x2c mm/kasan/report_generic.c:378 crc64_be_generic lib/crc/crc64-main.c:47 [inline] crc64_be+0xb8/0xe8 lib/crc/crc64-main.c:68 bch_crc64 drivers/md/bcache/util.h:529 [inline] read_super drivers/md/bcache/super.c:208 [inline] register_bcache+0x9a4/0x13d8 drivers/md/bcache/super.c:2601 kobj_attr_store+0x6c/0x90 lib/kobject.c:840 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x51c/0xa0c fs/read_write.c:687 ksys_write+0x12c/0x228 fs/read_write.c:739 __do_sys_write fs/read_write.c:750 [inline] __se_sys_write fs/read_write.c:747 [inline] __arm64_sys_write+0x84/0x98 fs/read_write.c:747 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:738 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:757 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff0000dd543af0 pfn:0x11d543 flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000000000 fffffdffc3754688 fffffdffc3755348 0000000000000000 raw: ffff0000dd543af0 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000dd542f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff0000dd542f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff0000dd543000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff0000dd543080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff0000dd543100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== bcache: register_bcache() error : Bad checksum --- 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 syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. 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