From 1f9f4f4777e7958e5c1fbdfd9ddf4207dc00a40f Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: Tue, 25 Jul 2023 10:37:19 +0900
Subject: [PATCH 1/3] tracing/probes: Fix to add NULL check for BTF APIs
Since find_btf_func_param() abd btf_type_by_id() can return NULL,
the caller must check the return value correctly.
Link: https://lore.kernel.org/all/169024903951.395371.11361556840733470934.stgit@devnote2/
Fixes: b576e09701c7 ("tracing/probes: Support function parameters if BTF is available")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_probe.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index b2b726bea1f9e..c68a727078525 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -386,12 +386,12 @@ static const struct btf_type *find_btf_func_proto(const char *funcname)
/* Get BTF_KIND_FUNC type */
t = btf_type_by_id(btf, id);
- if (!btf_type_is_func(t))
+ if (!t || !btf_type_is_func(t))
return ERR_PTR(-ENOENT);
/* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
t = btf_type_by_id(btf, t->type);
- if (!btf_type_is_func_proto(t))
+ if (!t || !btf_type_is_func_proto(t))
return ERR_PTR(-ENOENT);
return t;
@@ -443,7 +443,7 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code,
if (!ctx->params) {
params = find_btf_func_param(ctx->funcname, &ctx->nr_params,
ctx->flags & TPARG_FL_TPOINT);
- if (IS_ERR(params)) {
+ if (IS_ERR_OR_NULL(params)) {
trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
return PTR_ERR(params);
}
@@ -1273,7 +1273,7 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
params = find_btf_func_param(ctx->funcname, &nr_params,
ctx->flags & TPARG_FL_TPOINT);
- if (IS_ERR(params)) {
+ if (IS_ERR_OR_NULL(params)) {
if (args_idx != -1) {
/* $arg* requires BTF info */
trace_probe_log_err(0, NOSUP_BTFARG);
From 02ab7234fc69695736d60b34044fe591689ffadd Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: Tue, 25 Jul 2023 10:37:29 +0900
Subject: [PATCH 2/3] selftests/ftrace: Fix to check fprobe event eneblement
Fix to check the availability of fprobe and kprobes for
add_remove_btfarg.tc.
Only if both kprobe and fprobe are not supported, it should return
"unsupported".
Link: https://lore.kernel.org/all/169024904889.395371.17998733386857387118.stgit@devnote2/
Fixes: 4231f30fcc34 ("selftests/ftrace: Add BTF arguments test cases")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
.../selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc
index b89de17716555..f34b14ef9781f 100644
--- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc
@@ -13,7 +13,7 @@ if grep -qF "f[:[<group>/][<event>]] <func-name>[%return] [<args>]" README ; the
FPROBES=yes
fi
-if [ -z "$KPROBES" -a "$FPROBES" ] ; then
+if [ -z "$KPROBES" -a -z "$FPROBES" ] ; then
exit_unsupported
fi
From de02f2ac5d8cfb311f44f2bf144cc20002f1fbbd Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: Tue, 11 Jul 2023 10:50:47 +0900
Subject: [PATCH 3/3] kprobes: Prohibit probing on CFI preamble symbol
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.
Link: https://lore.kernel.org/all/168904024679.116016.18089228029322008512.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/kprobes.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1fc6095d502d9..ca385b61d5467 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;
}