Re: [Patch V3] crypto: x86/sha1 : Fix reads beyond the number of blocks passed

[Jan Stancek]

- Original Message -
> On Wed, 2017-08-02 at 10:13 -0700, Megha Dey wrote:
> > It was reported that the sha1 AVX2 function(sha1_transform_avx2) is
> > reading ahead beyond its intended data, and causing a crash if the next
> > block is beyond page boundary:
> > http://marc.info/?l=linux-crypto-vger=149373371023377
> > 
> > This patch makes sure that there is no overflow for any buffer length.
> > 
> > It passes the tests written by Jan Stancek that revealed this problem:
> > https://github.com/jstancek/sha1-avx2-crash
> 
> Hi Jan,
> 
> Is it ok to add your Tested-by?

Yes, v3 patch is exactly the diff I was testing.

Regards,
Jan

Re: [Patch V3] crypto: x86/sha1 : Fix reads beyond the number of blocks passed

[Megha Dey]

On Wed, 2017-08-02 at 10:13 -0700, Megha Dey wrote:
> It was reported that the sha1 AVX2 function(sha1_transform_avx2) is
> reading ahead beyond its intended data, and causing a crash if the next
> block is beyond page boundary:
> http://marc.info/?l=linux-crypto-vger=149373371023377
> 
> This patch makes sure that there is no overflow for any buffer length.
> 
> It passes the tests written by Jan Stancek that revealed this problem:
> https://github.com/jstancek/sha1-avx2-crash

Hi Jan,

Is it ok to add your Tested-by?

> 
> I have re-enabled sha1-avx2 by reverting commit
> b82ce24426a4071da9529d726057e4e642948667
> 
> Originally-by: Ilya Albrekht 
> Signed-off-by: Megha Dey 
> Reported-by: Jan Stancek 
> ---
>  arch/x86/crypto/sha1_avx2_x86_64_asm.S | 67 
> ++
>  arch/x86/crypto/sha1_ssse3_glue.c  |  2 +-
>  2 files changed, 37 insertions(+), 32 deletions(-)
> 
> diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S 
> b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> index 1cd792d..1eab79c 100644
> --- a/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> +++ b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
> @@ -117,11 +117,10 @@
>   .set T1, REG_T1
>  .endm
>  
> -#define K_BASE   %r8
>  #define HASH_PTR %r9
> +#define BLOCKS_CTR   %r8
>  #define BUFFER_PTR   %r10
>  #define BUFFER_PTR2  %r13
> -#define BUFFER_END   %r11
>  
>  #define PRECALC_BUF  %r14
>  #define WK_BUF   %r15
> @@ -205,14 +204,14 @@
>* blended AVX2 and ALU instruction scheduling
>* 1 vector iteration per 8 rounds
>*/
> - vmovdqu ((i * 2) + PRECALC_OFFSET)(BUFFER_PTR), W_TMP
> + vmovdqu (i * 2)(BUFFER_PTR), W_TMP
>   .elseif ((i & 7) == 1)
> - vinsertf128 $1, (((i-1) * 2)+PRECALC_OFFSET)(BUFFER_PTR2),\
> + vinsertf128 $1, ((i-1) * 2)(BUFFER_PTR2),\
>WY_TMP, WY_TMP
>   .elseif ((i & 7) == 2)
>   vpshufb YMM_SHUFB_BSWAP, WY_TMP, WY
>   .elseif ((i & 7) == 4)
> - vpaddd  K_XMM(K_BASE), WY, WY_TMP
> + vpaddd  K_XMM + K_XMM_AR(%rip), WY, WY_TMP
>   .elseif ((i & 7) == 7)
>   vmovdqu  WY_TMP, PRECALC_WK(i&~7)
>  
> @@ -255,7 +254,7 @@
>   vpxor   WY, WY_TMP, WY_TMP
>   .elseif ((i & 7) == 7)
>   vpxor   WY_TMP2, WY_TMP, WY
> - vpaddd  K_XMM(K_BASE), WY, WY_TMP
> + vpaddd  K_XMM + K_XMM_AR(%rip), WY, WY_TMP
>   vmovdqu WY_TMP, PRECALC_WK(i&~7)
>  
>   PRECALC_ROTATE_WY
> @@ -291,7 +290,7 @@
>   vpsrld  $30, WY, WY
>   vporWY, WY_TMP, WY
>   .elseif ((i & 7) == 7)
> - vpaddd  K_XMM(K_BASE), WY, WY_TMP
> + vpaddd  K_XMM + K_XMM_AR(%rip), WY, WY_TMP
>   vmovdqu WY_TMP, PRECALC_WK(i&~7)
>  
>   PRECALC_ROTATE_WY
> @@ -446,6 +445,16 @@
>  
>  .endm
>  
> +/* Add constant only if (%2 > %3) condition met (uses RTA as temp)
> + * %1 + %2 >= %3 ? %4 : 0
> + */
> +.macro ADD_IF_GE a, b, c, d
> + mov \a, RTA
> + add $\d, RTA
> + cmp $\c, \b
> + cmovge  RTA, \a
> +.endm
> +
>  /*
>   * macro implements 80 rounds of SHA-1, for multiple blocks with s/w 
> pipelining
>   */
> @@ -463,13 +472,16 @@
>   lea (2*4*80+32)(%rsp), WK_BUF
>  
>   # Precalc WK for first 2 blocks
> - PRECALC_OFFSET = 0
> + ADD_IF_GE BUFFER_PTR2, BLOCKS_CTR, 2, 64
>   .set i, 0
>   .rept160
>   PRECALC i
>   .set i, i + 1
>   .endr
> - PRECALC_OFFSET = 128
> +
> + /* Go to next block if needed */
> + ADD_IF_GE BUFFER_PTR, BLOCKS_CTR, 3, 128
> + ADD_IF_GE BUFFER_PTR2, BLOCKS_CTR, 4, 128
>   xchgWK_BUF, PRECALC_BUF
>  
>   .align 32
> @@ -479,8 +491,8 @@ _loop:
>* we use K_BASE value as a signal of a last block,
>* it is set below by: cmovae BUFFER_PTR, K_BASE
>*/
> - cmp K_BASE, BUFFER_PTR
> - jne _begin
> + test BLOCKS_CTR, BLOCKS_CTR
> + jnz _begin
>   .align 32
>   jmp _end
>   .align 32
> @@ -512,10 +524,10 @@ _loop0:
>   .set j, j+2
>   .endr
>  
> - add $(2*64), BUFFER_PTR   /* move to next odd-64-byte block */
> - cmp BUFFER_END, BUFFER_PTR/* is current block the last one? */
> - cmovae  K_BASE, BUFFER_PTR  /* signal the last iteration smartly */
> -
> + /* Update Counter */
> + sub $1, BLOCKS_CTR
> + /* Move to the next block only if needed*/
> + ADD_IF_GE BUFFER_PTR, BLOCKS_CTR, 4, 128
>   /*
>* rounds
>* 60,62,64,66,68
> @@ -532,8 +544,8 @@ _loop0:
>   UPDATE_HASH 12(HASH_PTR), D
>   UPDATE_HASH 16(HASH_PTR), E
>  
> - cmp K_BASE, BUFFER_PTR  /* is current block the last one? */
> - je  _loop
> + testBLOCKS_CTR, BLOCKS_CTR
> +