From 7976c1492571a5fb234c416559a0d9790855c635 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 23 Feb 2022 08:07:01 +0100 Subject: crypto: crypto_xor - use helpers for unaligned accesses Dereferencing a misaligned pointer is undefined behavior in C, and may result in codegen on architectures such as ARM that trigger alignments traps and expensive fixups in software. Instead, use the get_aligned()/put_aligned() accessors, which are cheap or even completely free when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y. In the converse case, the prior alignment checks ensure that the casts are safe, and so no unaligned accessors are necessary. Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- crypto/algapi.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) (limited to 'crypto/algapi.c') diff --git a/crypto/algapi.c b/crypto/algapi.c index 53c5149e6abf..b078e7a6e64c 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -1022,7 +1022,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len) } while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) { - *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2; + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { + u64 l = get_unaligned((u64 *)src1) ^ + get_unaligned((u64 *)src2); + put_unaligned(l, (u64 *)dst); + } else { + *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2; + } dst += 8; src1 += 8; src2 += 8; @@ -1030,7 +1036,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len) } while (len >= 4 && !(relalign & 3)) { - *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2; + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { + u32 l = get_unaligned((u32 *)src1) ^ + get_unaligned((u32 *)src2); + put_unaligned(l, (u32 *)dst); + } else { + *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2; + } dst += 4; src1 += 4; src2 += 4; @@ -1038,7 +1050,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len) } while (len >= 2 && !(relalign & 1)) { - *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2; + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { + u16 l = get_unaligned((u16 *)src1) ^ + get_unaligned((u16 *)src2); + put_unaligned(l, (u16 *)dst); + } else { + *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2; + } dst += 2; src1 += 2; src2 += 2; -- cgit