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crypto: hash - Zap unaligned buffers

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Some unaligned buffers on the stack weren't zapped properly which
may cause secret data to be leaked.  This patch fixes them by doing
a zero memset.

It is also possible for us to place random kernel stack contents
in the digest buffer if a digest operation fails.  This is fixed
by only copying if the operation succeeded.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2009-07-14 21:35:36 +08:00
parent 500b3e3c3d
commit 8c32c516eb
2 changed files with 12 additions and 5 deletions
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3
crypto/ahash.c
View file

@ -152,8 +152,7 @@ static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
memcpy(alignbuffer, key, keylen);
ret = ahash->setkey(tfm, alignbuffer, keylen);
memset(alignbuffer, 0, keylen);
kfree(buffer);
kzfree(buffer);
return ret;
}

14
crypto/shash.c
View file

@ -45,8 +45,7 @@ static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
memcpy(alignbuffer, key, keylen);
err = shash->setkey(tfm, alignbuffer, keylen);
memset(alignbuffer, 0, keylen);
kfree(buffer);
kzfree(buffer);
return err;
}
@ -79,13 +78,16 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
((unsigned long)data & alignmask);
u8 buf[shash_align_buffer_size(unaligned_len, alignmask)]
__attribute__ ((aligned));
int err;
if (unaligned_len > len)
unaligned_len = len;
memcpy(buf, data, unaligned_len);
err = shash->update(desc, buf, unaligned_len);
memset(buf, 0, unaligned_len);
return shash->update(desc, buf, unaligned_len) ?:
return err ?:
shash->update(desc, data + unaligned_len, len - unaligned_len);
}
@ -114,7 +116,13 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
int err;
err = shash->final(desc, buf);
if (err)
goto out;
memcpy(out, buf, ds);
out:
memset(buf, 0, ds);
return err;
}