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nbd-client: Stricter enforcing of structured reply spec 

Ensure that the server is not sending unexpected chunk lengths
for either the NONE or the OFFSET_DATA chunk, nor unexpected
hole length for OFFSET_HOLE.  This will flag any server as
broken that responds to a zero-length read with an OFFSET_DATA
(what our server currently does, but that's about to be fixed)
or with OFFSET_HOLE, even though we previously fixed our client
to never be able to send such a request over the wire.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171108215703.9295-7-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
This commit is contained in:
Eric Blake 2017-11-08 15:57:02 -06:00
parent 9d8f818cde
commit b4176cb314
1 changed files with 9 additions and 2 deletions
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11
block/nbd-client.c
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@ -216,7 +216,7 @@ static int nbd_parse_offset_hole_payload(NBDStructuredReplyChunk *chunk,
offset = payload_advance64(&payload);
hole_size = payload_advance32(&payload);
if (offset < orig_offset || hole_size > qiov->size ||
if (!hole_size || offset < orig_offset || hole_size > qiov->size ||
offset > orig_offset + qiov->size - hole_size) {
error_setg(errp, "Protocol error: server sent chunk exceeding requested"
" region");
@ -281,7 +281,8 @@ static int nbd_co_receive_offset_data_payload(NBDClientSession *s,
assert(nbd_reply_is_structured(&s->reply));
if (chunk->length < sizeof(offset)) {
/* The NBD spec requires at least one byte of payload */
if (chunk->length <= sizeof(offset)) {
error_setg(errp, "Protocol error: invalid payload for "
"NBD_REPLY_TYPE_OFFSET_DATA");
return -EINVAL;
@ -293,6 +294,7 @@ static int nbd_co_receive_offset_data_payload(NBDClientSession *s,
be64_to_cpus(&offset);
data_size = chunk->length - sizeof(offset);
assert(data_size);
if (offset < orig_offset || data_size > qiov->size ||
offset > orig_offset + qiov->size - data_size) {
error_setg(errp, "Protocol error: server sent chunk exceeding requested"
@ -411,6 +413,11 @@ static coroutine_fn int nbd_co_do_receive_one_chunk(
" NBD_REPLY_FLAG_DONE flag set");
return -EINVAL;
}
if (chunk->length) {
error_setg(errp, "Protocol error: NBD_REPLY_TYPE_NONE chunk with"
" nonzero length");
return -EINVAL;
}
return 0;
}