The AVX2 implementation might waste up to a page of stack memory because of a wrong alignment calculation. This will, in the worst case, increase the stack usage of sha1_transform_avx2() alone to 5.4 kB -- way to big for a kernel function. Even worse, it might also allocate *less* bytes than needed if the stack pointer is already aligned bacause in that case the 'sub %rbx, %rsp' is effectively moving the stack pointer upwards, not downwards. Fix those issues by changing and simplifying the alignment calculation to use a 32 byte alignment, the alignment really needed. Cc: Chandramouli Narayanan <mouli@xxxxxxxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Marek Vasut <marex@xxxxxxx> Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx> --- arch/x86/crypto/sha1_avx2_x86_64_asm.S | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S b/arch/x86/crypto/sha1_avx2_x86_64_asm.S index 4f348544d1..bacac22b20 100644 --- a/arch/x86/crypto/sha1_avx2_x86_64_asm.S +++ b/arch/x86/crypto/sha1_avx2_x86_64_asm.S @@ -636,9 +636,7 @@ _loop3: /* Align stack */ mov %rsp, %rbx - and $(0x1000-1), %rbx - sub $(8+32), %rbx - sub %rbx, %rsp + and $~(0x20-1), %rsp push %rbx sub $RESERVE_STACK, %rsp @@ -665,8 +663,7 @@ _loop3: avx2_zeroupper add $RESERVE_STACK, %rsp - pop %rbx - add %rbx, %rsp + pop %rsp pop %r15 pop %r14 -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
