[PATCH v2 1/2] kprobes: Prohibit probing on CFI preamble symbol
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2023-07-11 01:51:30
Also in:
lkml
Subsystem:
kprobes, the rest · Maintainers:
Naveen N Rao, "David S. Miller", Masami Hiramatsu, Linus Torvalds
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> Do not allow to probe on "__cfi_" or "__pfx_" started symbol, because those are used for CFI and not executed. Probing it will break the CFI. Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- Changes in v2: - Check "__pfx_" prefix functions too. - Make the check unconditional. --- kernel/kprobes.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 00e177de91cc..3da9726232ff 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c@@ -1545,6 +1545,17 @@ static int check_ftrace_location(struct kprobe *p) return 0; } +static bool is_cfi_preamble_symbol(unsigned long addr) +{ + char symbuf[KSYM_NAME_LEN]; + + if (lookup_symbol_name(addr, symbuf)) + return false; + + return str_has_prefix("__cfi_", symbuf) || + str_has_prefix("__pfx_", symbuf); +} + static int check_kprobe_address_safe(struct kprobe *p, struct module **probed_mod) {
@@ -1563,7 +1574,8 @@ static int check_kprobe_address_safe(struct kprobe *p, within_kprobe_blacklist((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)) { + find_bug((unsigned long)p->addr) || + is_cfi_preamble_symbol((unsigned long)p->addr)) { ret = -EINVAL; goto out; }