The patch below does not apply to the 6.6-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-6.6.y git checkout FETCH_HEAD git cherry-pick -x 44e8241c51f762aafa50ed116da68fd6ecdcc954 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025110921-resonant-acrobat-064c@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 44e8241c51f762aafa50ed116da68fd6ecdcc954 Mon Sep 17 00:00:00 2001 From: Eric Biggers ebiggers@kernel.org Date: Mon, 3 Nov 2025 21:49:06 -0800 Subject: [PATCH] lib/crypto: arm/curve25519: Disable on CPU_BIG_ENDIAN

On big endian arm kernels, the arm optimized Curve25519 code produces incorrect outputs and fails the Curve25519 test. This has been true ever since this code was added.

It seems that hardly anyone (or even no one?) actually uses big endian arm kernels. But as long as they're ostensibly supported, we should disable this code on them so that it's not accidentally used.

Note: for future-proofing, use !CPU_BIG_ENDIAN instead of CPU_LITTLE_ENDIAN. Both of these are arch-specific options that could get removed in the future if big endian support gets dropped.

Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation") Cc: stable@vger.kernel.org Acked-by: Ard Biesheuvel ardb@kernel.org Link: https://lore.kernel.org/r/20251104054906.716914-1-ebiggers@kernel.org Signed-off-by: Eric Biggers ebiggers@kernel.org

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig index 8886055e938f..16859c6226dd 100644 --- a/lib/crypto/Kconfig +++ b/lib/crypto/Kconfig @@ -64,7 +64,7 @@ config CRYPTO_LIB_CURVE25519 config CRYPTO_LIB_CURVE25519_ARCH bool depends on CRYPTO_LIB_CURVE25519 && !UML && !KMSAN - default y if ARM && KERNEL_MODE_NEON + default y if ARM && KERNEL_MODE_NEON && !CPU_BIG_ENDIAN default y if PPC64 && CPU_LITTLE_ENDIAN default y if X86_64