crypto: x86/sha256-mb - fix digest copy in sha256_mb_mgr_get_comp_job_avx2()

Commit Message

Eric Biggers June 29, 2018, 9:14 p.m. UTC

From: Eric Biggers <[e-mail]>

There is a copy-paste error where sha256_mb_mgr_get_comp_job_avx2()
copies the SHA-256 digest state from sha256_mb_mgr::args::digest to
job_sha256::result_digest.  Consequently, the sha256_mb algorithm
sometimes calculates the wrong digest.  Fix it.

Reproducer using AF_ALG:

    #include <assert.h>
    #include <linux/if_alg.h>
    #include <stdio.h>
    #include <string.h>
    #include <sys/socket.h>
    #include <unistd.h>

    static const __u8 expected[32] =
        "\xad\x7f\xac\xb2\x58\x6f\xc6\xe9\x66\xc0\x04\xd7\xd1\xd1\x6b\x02"
        "\x4f\x58\x05\xff\x7c\xb4\x7c\x7a\x85\xda\xbd\x8b\x48\x89\x2c\xa7";

    int main()
    {
        int fd;
        struct sockaddr_alg addr = {
            .salg_type = "hash",
            .salg_name = "sha256_mb",
        };
        __u8 data[4096] = { 0 };
        __u8 digest[32];
        int ret;
        int i;

        fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
        bind(fd, (void *)&addr, sizeof(addr));
        fork();
        fd = accept(fd, 0, 0);
        do {
            ret = write(fd, data, 4096);
            assert(ret == 4096);
            ret = read(fd, digest, 32);
            assert(ret == 32);
        } while (memcmp(digest, expected, 32) == 0);

        printf("wrong digest: ");
        for (i = 0; i < 32; i++)
            printf("%02x", digest[i]);
        printf("\n");
    }

Output was:

    wrong digest: ad7facb2000000000000000000000000ffffffef7cb47c7a85dabd8b48892ca7

Fixes: 172b1d6b5a93 ("crypto: sha256-mb - fix ctx pointer and digest copy")
Cc: <[e-mail]> # v4.8+
Signed-off-by: Eric Biggers <[e-mail]>
---
 arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Herbert Xu July 8, 2018, 4:45 p.m. UTC | #1

On Fri, Jun 29, 2018 at 02:14:35PM -0700, Eric Biggers wrote:
> From: Eric Biggers <[e-mail]>
> 
> There is a copy-paste error where sha256_mb_mgr_get_comp_job_avx2()
> copies the SHA-256 digest state from sha256_mb_mgr::args::digest to
> job_sha256::result_digest.  Consequently, the sha256_mb algorithm
> sometimes calculates the wrong digest.  Fix it.
> 
> Reproducer using AF_ALG:
> 
>     #include <assert.h>
>     #include <linux/if_alg.h>
>     #include <stdio.h>
>     #include <string.h>
>     #include <sys/socket.h>
>     #include <unistd.h>
> 
>     static const __u8 expected[32] =
>         "\xad\x7f\xac\xb2\x58\x6f\xc6\xe9\x66\xc0\x04\xd7\xd1\xd1\x6b\x02"
>         "\x4f\x58\x05\xff\x7c\xb4\x7c\x7a\x85\xda\xbd\x8b\x48\x89\x2c\xa7";
> 
>     int main()
>     {
>         int fd;
>         struct sockaddr_alg addr = {
>             .salg_type = "hash",
>             .salg_name = "sha256_mb",
>         };
>         __u8 data[4096] = { 0 };
>         __u8 digest[32];
>         int ret;
>         int i;
> 
>         fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
>         bind(fd, (void *)&addr, sizeof(addr));
>         fork();
>         fd = accept(fd, 0, 0);
>         do {
>             ret = write(fd, data, 4096);
>             assert(ret == 4096);
>             ret = read(fd, digest, 32);
>             assert(ret == 32);
>         } while (memcmp(digest, expected, 32) == 0);
> 
>         printf("wrong digest: ");
>         for (i = 0; i < 32; i++)
>             printf("%02x", digest[i]);
>         printf("\n");
>     }
> 
> Output was:
> 
>     wrong digest: ad7facb2000000000000000000000000ffffffef7cb47c7a85dabd8b48892ca7
> 
> Fixes: 172b1d6b5a93 ("crypto: sha256-mb - fix ctx pointer and digest copy")
> Cc: <[e-mail]> # v4.8+
> Signed-off-by: Eric Biggers <[e-mail]>

Patch applied.  Thanks.

Patch

diff --git a/arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S b/arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S
index 16c4ccb1f154..d2364c55bbde 100644
--- a/arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S
+++ b/arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S
@@ -265,7 +265,7 @@  ENTRY(sha256_mb_mgr_get_comp_job_avx2)
 	vpinsrd	$1, _args_digest+1*32(state, idx, 4), %xmm0, %xmm0
 	vpinsrd	$2, _args_digest+2*32(state, idx, 4), %xmm0, %xmm0
 	vpinsrd	$3, _args_digest+3*32(state, idx, 4), %xmm0, %xmm0
-	vmovd   _args_digest(state , idx, 4) , %xmm0
+	vmovd	_args_digest+4*32(state, idx, 4), %xmm1
 	vpinsrd	$1, _args_digest+5*32(state, idx, 4), %xmm1, %xmm1
 	vpinsrd	$2, _args_digest+6*32(state, idx, 4), %xmm1, %xmm1
 	vpinsrd	$3, _args_digest+7*32(state, idx, 4), %xmm1, %xmm1