Syzkaller reported a BUG on arm64: Unrecoverable kprobe detected. Dumping kprobe: Name: (null) Offset: 0 Address: 0xffffa00010019000 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:235! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: CPU: 1 PID: 31060 Comm: syz-executor.6 Not tainted 5.10.0 #11 ... Call trace: reenter_kprobe arch/arm64/kernel/probes/kprobes.c:234 [inline] kprobe_handler+0x23c/0x26c arch/arm64/kernel/probes/kprobes.c:339 kprobe_breakpoint_handler+0x24/0x34 arch/arm64/kernel/probes/kprobes.c:406 call_break_hook+0xf4/0x13c arch/arm64/kernel/debug-monitors.c:322 brk_handler+0x2c/0xa0 arch/arm64/kernel/debug-monitors.c:329 do_debug_exception+0x140/0x230 arch/arm64/mm/fault.c:867 el1_dbg+0x38/0x50 arch/arm64/kernel/entry-common.c:182 el1_sync_handler+0xf4/0x150 arch/arm64/kernel/entry-common.c:219 el1_sync+0x74/0x100 arch/arm64/kernel/entry.S:665 0xffffa00010019000 do_futex+0x2f4/0x370 kernel/futex.c:3735 __do_sys_futex kernel/futex.c:3798 [inline] __se_sys_futex kernel/futex.c:3764 [inline] __arm64_sys_futex+0x168/0x3a0 kernel/futex.c:3764 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155 do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217 el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353 el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369 el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683 Code: 91018360 97ff1838 aa1703e0 97ff1fdf (d4210000) ---[ end trace 767503e946e01b15 ]--- Syzbot tried to porbe on a kprobe_insn_slot. kprobe will replace instruciton with a break and store the origin one on kprobe_insn_slot. However these slots are not in .kprobes.text and exported by perf_event_ksymbol so can be probed by perf interface. Probing these slots will triggers kprobe handler inside single step process and for some architectures such as arm64 this will causes a bug(). These slots are kprobe process so they should not be probed anyway. Add kprobe_insn_slot check when register_kprobe to forbid probing on these slots. Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx> --- kernel/kprobes.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f214f8c088ed..3e798b62db70 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1562,6 +1562,8 @@ static int check_kprobe_address_safe(struct kprobe *p, /* Ensure it is not in reserved area nor out of text */ if (!kernel_text_address((unsigned long) p->addr) || within_kprobe_blacklist((unsigned long) p->addr) || + is_kprobe_insn_slot((unsigned long) p->addr) || + is_kprobe_optinsn_slot((unsigned long) p->addr) || jump_label_text_reserved(p->addr, p->addr) || static_call_text_reserved(p->addr, p->addr) || find_bug((unsigned long)p->addr)) { -- 2.17.1