3 files changed, 65 insertions, 17 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 7a13e6ac6327..88589d74a892 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2423,7 +2423,7 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip,
 	kprobe_multi_link_prog_run(link, entry_ip, regs);
 }
 
-static int symbols_cmp(const void *a, const void *b)
+static int symbols_cmp_r(const void *a, const void *b, const void *priv)
 {
 	const char **str_a = (const char **) a;
 	const char **str_b = (const char **) b;
@@ -2431,6 +2431,28 @@ static int symbols_cmp(const void *a, const void *b)
 	return strcmp(*str_a, *str_b);
 }
 
+struct multi_symbols_sort {
+	const char **funcs;
+	u64 *cookies;
+};
+
+static void symbols_swap_r(void *a, void *b, int size, const void *priv)
+{
+	const struct multi_symbols_sort *data = priv;
+	const char **name_a = a, **name_b = b;
+
+	swap(*name_a, *name_b);
+
+	/* If defined, swap also related cookies. */
+	if (data->cookies) {
+		u64 *cookie_a, *cookie_b;
+
+		cookie_a = data->cookies + (name_a - data->funcs);
+		cookie_b = data->cookies + (name_b - data->funcs);
+		swap(*cookie_a, *cookie_b);
+	}
+}
+
 int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 {
 	struct bpf_kprobe_multi_link *link = NULL;
@@ -2468,38 +2490,46 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	if (!addrs)
 		return -ENOMEM;
 
+	ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
+	if (ucookies) {
+		cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
+		if (!cookies) {
+			err = -ENOMEM;
+			goto error;
+		}
+		if (copy_from_user(cookies, ucookies, size)) {
+			err = -EFAULT;
+			goto error;
+		}
+	}
+
 	if (uaddrs) {
 		if (copy_from_user(addrs, uaddrs, size)) {
 			err = -EFAULT;
 			goto error;
 		}
 	} else {
+		struct multi_symbols_sort data = {
+			.cookies = cookies,
+		};
 		struct user_syms us;
 
 		err = copy_user_syms(&us, usyms, cnt);
 		if (err)
 			goto error;
 
-		sort(us.syms, cnt, sizeof(*us.syms), symbols_cmp, NULL);
+		if (cookies)
+			data.funcs = us.syms;
+
+		sort_r(us.syms, cnt, sizeof(*us.syms), symbols_cmp_r,
+		       symbols_swap_r, &data);
+
 		err = ftrace_lookup_symbols(us.syms, cnt, addrs);
 		free_user_syms(&us);
 		if (err)
 			goto error;
 	}
 
-	ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
-	if (ucookies) {
-		cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
-		if (!cookies) {
-			err = -ENOMEM;
-			goto error;
-		}
-		if (copy_from_user(cookies, ucookies, size)) {
-			err = -EFAULT;
-			goto error;
-		}
-	}
-
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
 	if (!link) {
 		err = -ENOMEM;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index e750fe141a60..601ccf1b2f09 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -8029,15 +8029,23 @@ static int kallsyms_callback(void *data, const char *name,
 			     struct module *mod, unsigned long addr)
 {
 	struct kallsyms_data *args = data;
+	const char **sym;
+	int idx;
 
-	if (!bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp))
+	sym = bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp);
+	if (!sym)
+		return 0;
+
+	idx = sym - args->syms;
+	if (args->addrs[idx])
 		return 0;
 
 	addr = ftrace_location(addr);
 	if (!addr)
 		return 0;
 
-	args->addrs[args->found++] = addr;
+	args->addrs[idx] = addr;
+	args->found++;
 	return args->found == args->cnt ? 1 : 0;
 }
 
@@ -8062,6 +8070,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a
 	struct kallsyms_data args;
 	int err;
 
+	memset(addrs, 0, sizeof(*addrs) * cnt);
 	args.addrs = addrs;
 	args.syms = sorted_syms;
 	args.cnt = cnt;
diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
index b56833700d23..c69d82273ce7 100644
--- a/kernel/trace/rethook.c
+++ b/kernel/trace/rethook.c
@@ -154,6 +154,15 @@ struct rethook_node *rethook_try_get(struct rethook *rh)
 	if (unlikely(!handler))
 		return NULL;
 
+	/*
+	 * This expects the caller will set up a rethook on a function entry.
+	 * When the function returns, the rethook will eventually be reclaimed
+	 * or released in the rethook_recycle() with call_rcu().
+	 * This means the caller must be run in the RCU-availabe context.
+	 */
+	if (unlikely(!rcu_is_watching()))
+		return NULL;
+
 	fn = freelist_try_get(&rh->pool);
 	if (!fn)
 		return NULL;