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    Subject[PATCH 4.18 13/22] crypto: x86/sha256-mb - fix digest copy in sha256_mb_mgr_get_comp_job_avx2()
    Date
    4.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Biggers <ebiggers@google.com>

    commit af839b4e546613aed1fbd64def73956aa98631e7 upstream.

    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: <stable@vger.kernel.org> # v4.8+
    Signed-off-by: Eric Biggers <ebiggers@google.com>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/crypto/sha256-mb/sha256_mb_mgr_flush_avx2.S | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- 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

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