Patch "crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     crypto-ecdh_helper-ensure-len-secret.len-in-decode_k.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 35f9f257a30f0fb5074a4ed455e01daa55310790
Author: Daniele Alessandrelli <daniele.alessandrelli@xxxxxxxxx>
Date:   Wed Feb 3 11:28:37 2021 +0000

    crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()
    
    [ Upstream commit a53ab94eb6850c3657392e2d2ce9b38c387a2633 ]
    
    The length ('len' parameter) passed to crypto_ecdh_decode_key() is never
    checked against the length encoded in the passed buffer ('buf'
    parameter). This could lead to an out-of-bounds access when the passed
    length is less than the encoded length.
    
    Add a check to prevent that.
    
    Fixes: 3c4b23901a0c7 ("crypto: ecdh - Add ECDH software support")
    Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@xxxxxxxxx>
    Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/crypto/ecdh_helper.c b/crypto/ecdh_helper.c
index 66fcb2ea81544..fca63b559f655 100644
--- a/crypto/ecdh_helper.c
+++ b/crypto/ecdh_helper.c
@@ -67,6 +67,9 @@ int crypto_ecdh_decode_key(const char *buf, unsigned int len,
 	if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
 		return -EINVAL;
 
+	if (unlikely(len < secret.len))
+		return -EINVAL;
+
 	ptr = ecdh_unpack_data(&params->curve_id, ptr, sizeof(params->curve_id));
 	ptr = ecdh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
 	if (secret.len != crypto_ecdh_key_len(params))