crypto: hash - Zap unaligned buffers
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>
diff --git a/crypto/shash.c b/crypto/shash.c
index fd92c03..e543283 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -45,8 +45,7 @@
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 @@
((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 @@
int err;
err = shash->final(desc, buf);
+ if (err)
+ goto out;
+
memcpy(out, buf, ds);
+
+out:
+ memset(buf, 0, ds);
return err;
}