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Sat, 08 Aug 2026 13:07:30 -0700 (PDT) Date: Sat, 08 Aug 2026 13:07:30 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a778c82.01d0871a.3a0d52.006a.GAE@google.com> Subject: [syzbot] [raid?] UBSAN: shift-out-of-bounds in raid5_set_limits From: syzbot To: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, magiclinan@didiglobal.com, song@kernel.org, syzkaller-bugs@googlegroups.com, xiao@kernel.org, yukuai@fnnas.com, yukuai@fygo.io Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 7235a3e71949 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=169f0e49580000 kernel config: https://syzkaller.appspot.com/x/.config?x=ccf4bea59f67007 dashboard link: https://syzkaller.appspot.com/bug?extid=de94ddbfff0c9e6fe030 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=143b0132580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=114717b9580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/fd45635beaae/disk-7235a3e7.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/d7d2e6507223/vmlinux-7235a3e7.xz kernel image: https://storage.googleapis.com/syzbot-assets/b5b5d8de4cea/Image-7235a3e7.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+de94ddbfff0c9e6fe030@syzkaller.appspotmail.com md/raid:md0: not clean -- starting background reconstruction md/raid:md0: device ram0 operational as raid disk 0 md/raid:md0: raid level 5 active with 1 out of 1 devices, algorithm 0 ------------[ cut here ]------------ UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 shift exponent 64 is too large for 64-bit type 'unsigned long' CPU: 0 UID: 0 PID: 4920 Comm: syz.0.18 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 dump_stack+0x1c/0x28 lib/dump_stack.c:129 ubsan_epilogue+0x14/0x48 lib/ubsan.c:233 __ubsan_handle_shift_out_of_bounds+0x224/0x264 lib/ubsan.c:494 __roundup_pow_of_two include/linux/log2.h:57 [inline] raid5_set_limits+0x470/0x510 drivers/md/raid5.c:7835 raid5_run+0x1554/0x1b68 drivers/md/raid5.c:8133 md_run+0xb9c/0x1a6c drivers/md/md.c:6760 do_md_run+0x4c/0x4e4 drivers/md/md.c:6861 array_state_store+0x7a8/0xce8 drivers/md/md.c:-1 md_attr_store+0x304/0x438 drivers/md/md.c:6137 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:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 ---[ end trace ]--- --- 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