[PATCH] bpf: crypto: reject unterminated type and algorithm names

[Pengpeng Hou]

bpf_crypto_ctx_create() validates the overall size of
struct bpf_crypto_params, but it does not verify that the fixed-width
type[14] and algo[128] fields are NUL-terminated before passing them to
string consumers.

A caller can therefore fill either field without a terminator and cause
bpf_crypto_get_type(), has_algo(), or alloc_tfm() to read past the end
of the fixed buffer.

Reject parameter blocks whose type or algorithm name does not contain a
terminating NUL within the advertised field width.

Fixes: 3e1c6f35409f ("bpf: make common crypto API for TC/XDP programs")
Cc: stable@xxxxxxxxxxxxxxx

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 kernel/bpf/crypto.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 51f89cecefb4..8732689803a6 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -155,6 +155,12 @@ bpf_crypto_ctx_create(const struct bpf_crypto_params *params, u32 params__sz,
 		return NULL;
 	}
 
+	if (strnlen(params->type, sizeof(params->type)) == sizeof(params->type) ||
+	    strnlen(params->algo, sizeof(params->algo)) == sizeof(params->algo)) {
+		*err = -EINVAL;
+		return NULL;
+	}
+
 	type = bpf_crypto_get_type(params->type);
 	if (IS_ERR(type)) {
 		*err = PTR_ERR(type);
-- 
2.50.1 (Apple Git-155)