FAILED: patch "[PATCH] crypto: atmel-ecc - avoid stale fallback key after set_secret" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x f07a0d251db7606e4792d2610788fbcc7b2c0d12
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026083113-trough-translate-08c1@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f07a0d251db7606e4792d2610788fbcc7b2c0d12 Mon Sep 17 00:00:00 2001
From: Thorsten Blum <thorsten.blum@linux.dev>
Date: Wed, 8 Jul 2026 22:42:48 +0200
Subject: [PATCH] crypto: atmel-ecc - avoid stale fallback key after set_secret
 failure

Clear ->do_fallback before decoding a new ECDH secret and enable it only
after the software fallback accepts a caller-provided private key. This
avoids using a stale fallback key should crypto_kpp_set_secret() fail.

Fixes: 11105693fa05 ("crypto: atmel-ecc - introduce Microchip / Atmel ECC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index 8e13aeccf011..4add3b2ddd0b 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -82,6 +82,7 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 
 	kfree(ctx->public_key);
 	ctx->public_key = NULL;
+	ctx->do_fallback = false;
 
 	if (crypto_ecdh_decode_key(buf, len, &params) < 0) {
 		dev_err(&ctx->client->dev, "crypto_ecdh_decode_key failed\n");
@@ -89,8 +90,9 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 	}
 
 	if (params.key_size) {
-		ctx->do_fallback = true;
-		return crypto_kpp_set_secret(ctx->fallback, buf, len);
+		ret = crypto_kpp_set_secret(ctx->fallback, buf, len);
+		ctx->do_fallback = !ret;
+		return ret;
 	}
 
 	cmd = kmalloc_obj(*cmd);
@@ -101,8 +103,6 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 	if (!public_key)
 		goto free_cmd;
 
-	ctx->do_fallback = false;
-
 	atmel_i2c_init_genkey_cmd(cmd, DATA_SLOT_2);
 
 	ret = atmel_i2c_send_receive(ctx->client, cmd);