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crypto: dh - Don't permit 'key' or 'g' size longer than 'p'

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The "qat-dh" DH implementation assumes that 'key' and 'g' can be copied
into a buffer with size 'p_size'.  However it was never checked that
that was actually the case, which most likely allowed users to cause a
buffer underflow via KEYCTL_DH_COMPUTE.

Fix this by updating crypto_dh_decode_key() to verify this precondition
for all DH implementations.

Fixes: c9839143ebbf ("crypto: qat - Add DH support")
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2017-11-05 18:30:46 -08:00 committed by Herbert Xu
parent 199512b123
commit ccd9888f14
1 changed files with 8 additions and 0 deletions
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8
crypto/dh_helper.c
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@ -83,6 +83,14 @@ int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
if (secret.len != crypto_dh_key_len(params))
return -EINVAL;
/*
* Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
* some drivers assume otherwise.
*/
if (params->key_size > params->p_size ||
params->g_size > params->p_size)
return -EINVAL;
/* Don't allocate memory. Set pointers to data within
* the given buffer
*/