Subject: [PATCH net v2 1/2] tools: ynl: make sure we always pass yarg to mnl_cb_run

From: Jakub Kicinski <[email-masked]>
Date: Tue, 20 Feb 2024 08:11:11 -0800

There is one common error handler in ynl - ynl_cb_error().
It expects priv to be a pointer to struct ynl_parse_arg AKA yarg.
To avoid potential crashes if we encounter a stray NLMSG_ERROR
always pass yarg as priv (or a struct which has it as the first
member).

ynl_cb_null() has a similar problem directly - it expects yarg
but priv passed by the caller is ys.

Found by code inspection.

Fixes: 86878f14d71a ("tools: ynl: user space helpers")
Acked-by: Nicolas Dichtel <[email-masked]>
Signed-off-by: Jakub Kicinski <[email-masked]>
---
Further cleanup to enforce the types in net-next..
---
CC: [email-masked]
CC: [email-masked]
---
 tools/net/ynl/lib/ynl.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c
index c82a7f41b31c..9e41c8c0cc99 100644
--- a/tools/net/ynl/lib/ynl.c
+++ b/tools/net/ynl/lib/ynl.c
@@ -466,6 +466,8 @@ ynl_gemsg_start_dump(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version)
 
 int ynl_recv_ack(struct ynl_sock *ys, int ret)
 {
+	struct ynl_parse_arg yarg = { .ys = ys, };
+
 	if (!ret) {
 		yerr(ys, YNL_ERROR_EXPECT_ACK,
 		     "Expecting an ACK but nothing received");
@@ -478,7 +480,7 @@ int ynl_recv_ack(struct ynl_sock *ys, int ret)
 		return ret;
 	}
 	return mnl_cb_run(ys->rx_buf, ret, ys->seq, ys->portid,
-			  ynl_cb_null, ys);
+			  ynl_cb_null, &yarg);
 }
 
 int ynl_cb_null(const struct nlmsghdr *nlh, void *data)
@@ -741,11 +743,14 @@ static int ynl_ntf_parse(struct ynl_sock *ys, const struct nlmsghdr *nlh)
 
 static int ynl_ntf_trampoline(const struct nlmsghdr *nlh, void *data)
 {
-	return ynl_ntf_parse((struct ynl_sock *)data, nlh);
+	struct ynl_parse_arg *yarg = data;
+
+	return ynl_ntf_parse(yarg->ys, nlh);
 }
 
 int ynl_ntf_check(struct ynl_sock *ys)
 {
+	struct ynl_parse_arg yarg = { .ys = ys, };
 	ssize_t len;
 	int err;
 
@@ -767,7 +772,7 @@ int ynl_ntf_check(struct ynl_sock *ys)
 			return len;
 
 		err = mnl_cb_run2(ys->rx_buf, len, ys->seq, ys->portid,
-				  ynl_ntf_trampoline, ys,
+				  ynl_ntf_trampoline, &yarg,
 				  ynl_cb_array, NLMSG_MIN_TYPE);
 		if (err < 0)
 			return err;
-- 
2.43.0