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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-02-23 08:07:01 +0100 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2022-03-03 10:49:20 +1200 |
| commit | 7976c1492571a5fb234c416559a0d9790855c635 (patch) | |
| tree | 34d455af015e3256902f25da54e17bb52c5aeed5 | |
| parent | 4920a4a7262dd1c647b515c05358ccbee0ab828c (diff) | |
| download | linux-7976c1492571a5fb234c416559a0d9790855c635.tar.gz | |
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 <ardb@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
| -rw-r--r-- | crypto/algapi.c | 24 | ||||
| -rw-r--r-- | include/crypto/algapi.h | 10 |
2 files changed, 29 insertions, 5 deletions
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; diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index f76ec723ceae..f50c5d1725da 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -13,6 +13,8 @@ #include <linux/list.h> #include <linux/types.h> +#include <asm/unaligned.h> + /* * Maximum values for blocksize and alignmask, used to allocate * static buffers that are big enough for any combination of @@ -154,9 +156,11 @@ static inline void crypto_xor(u8 *dst, const u8 *src, unsigned int size) (size % sizeof(unsigned long)) == 0) { unsigned long *d = (unsigned long *)dst; unsigned long *s = (unsigned long *)src; + unsigned long l; while (size > 0) { - *d++ ^= *s++; + l = get_unaligned(d) ^ get_unaligned(s++); + put_unaligned(l, d++); size -= sizeof(unsigned long); } } else { @@ -173,9 +177,11 @@ static inline void crypto_xor_cpy(u8 *dst, const u8 *src1, const u8 *src2, unsigned long *d = (unsigned long *)dst; unsigned long *s1 = (unsigned long *)src1; unsigned long *s2 = (unsigned long *)src2; + unsigned long l; while (size > 0) { - *d++ = *s1++ ^ *s2++; + l = get_unaligned(s1++) ^ get_unaligned(s2++); + put_unaligned(l, d++); size -= sizeof(unsigned long); } } else { |