6.16-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@kernel.org
commit 52c3e242f4d0043186b70d65460ba1767f27494a upstream.
Restore the SIMD usability check that was removed by commit 773426f4771b ("crypto: arm/poly1305 - Add block-only interface").
This safety check is cheap and is well worth eliminating a footgun. While the Poly1305 functions should not be called when SIMD registers are unusable, if they are anyway, they should just do the right thing instead of corrupting random tasks' registers and/or computing incorrect MACs. Fixing this is also needed for poly1305_kunit to pass.
Just use may_use_simd() instead of the original crypto_simd_usable(), since poly1305_kunit won't rely on crypto_simd_disabled_for_test.
Fixes: 773426f4771b ("crypto: arm/poly1305 - Add block-only interface") Cc: stable@vger.kernel.org Reviewed-by: Ard Biesheuvel ardb@kernel.org Link: https://lore.kernel.org/r/20250706231100.176113-3-ebiggers@kernel.org Signed-off-by: Eric Biggers ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/lib/crypto/poly1305-glue.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/arm/lib/crypto/poly1305-glue.c +++ b/arch/arm/lib/crypto/poly1305-glue.c @@ -7,6 +7,7 @@
#include <asm/hwcap.h> #include <asm/neon.h> +#include <asm/simd.h> #include <crypto/internal/poly1305.h> #include <linux/cpufeature.h> #include <linux/jump_label.h> @@ -39,7 +40,7 @@ void poly1305_blocks_arch(struct poly130 { len = round_down(len, POLY1305_BLOCK_SIZE); if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && - static_branch_likely(&have_neon)) { + static_branch_likely(&have_neon) && likely(may_use_simd())) { do { unsigned int todo = min_t(unsigned int, len, SZ_4K);