[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PATCH 04/14] nbd/client: Add safety check on chunk payload length
From: |
Eric Blake |
Subject: |
[PATCH 04/14] nbd/client: Add safety check on chunk payload length |
Date: |
Fri, 3 Dec 2021 17:15:29 -0600 |
Our existing use of structured replies either reads into a qiov capped
at 32M (NBD_CMD_READ) or caps allocation to 1000 bytes (see
NBD_MAX_MALLOC_PAYLOAD in block/nbd.c). But the existing length
checks are rather late; if we encounter a buggy (or malicious) server
that sends a super-large payload length, we should drop the connection
right then rather than assuming the layer on top will be careful.
This becomes more important when we permit 64-bit lengths which are
even more likely to have the potential for attempted denial of service
abuse.
Signed-off-by: Eric Blake <eblake@redhat.com>
---
nbd/client.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/nbd/client.c b/nbd/client.c
index 30d5383cb195..8f137c2320bb 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -1412,6 +1412,18 @@ static int nbd_receive_structured_reply_chunk(QIOChannel
*ioc,
chunk->handle = be64_to_cpu(chunk->handle);
chunk->length = be32_to_cpu(chunk->length);
+ /*
+ * Because we use BLOCK_STATUS with REQ_ONE, and cap READ requests
+ * at 32M, no valid server should send us payload larger than
+ * this. Even if we stopped using REQ_ONE, sane servers will cap
+ * the number of extents they return for block status.
+ */
+ if (chunk->length > NBD_MAX_BUFFER_SIZE + sizeof(NBDStructuredReadData)) {
+ error_setg(errp, "server chunk %" PRIu32 " (%s) payload is too long",
+ chunk->type, nbd_rep_lookup(chunk->type));
+ return -EINVAL;
+ }
+
return 0;
}
--
2.33.1
- Re: [PATCH] spec: Add NBD_OPT_EXTENDED_HEADERS, (continued)
- [PATCH 00/14] qemu patches for NBD_OPT_EXTENDED_HEADERS, Eric Blake, 2021/12/03
- [PATCH 01/14] nbd/server: Minor cleanups, Eric Blake, 2021/12/03
- [PATCH 02/14] qemu-io: Utilize 64-bit status during map, Eric Blake, 2021/12/03
- [PATCH 06/14] nbd: Prepare for 64-bit requests, Eric Blake, 2021/12/03
- [PATCH 05/14] nbd/server: Prepare for alternate-size headers, Eric Blake, 2021/12/03
- [PATCH 03/14] qemu-io: Allow larger write zeroes under no fallback, Eric Blake, 2021/12/03
- [PATCH 04/14] nbd/client: Add safety check on chunk payload length,
Eric Blake <=
- [PATCH 07/14] nbd: Add types for extended headers, Eric Blake, 2021/12/03
- [PATCH 08/14] nbd/server: Initial support for extended headers, Eric Blake, 2021/12/03
- [PATCH 11/14] nbd/client: Accept 64-bit hole chunks, Eric Blake, 2021/12/03
- [PATCH 09/14] nbd/server: Support 64-bit block status, Eric Blake, 2021/12/03
- [PATCH 12/14] nbd/client: Accept 64-bit block status chunks, Eric Blake, 2021/12/03
- [PATCH 13/14] nbd/client: Request extended headers during negotiation, Eric Blake, 2021/12/03
- [PATCH 10/14] nbd/client: Initial support for extended headers, Eric Blake, 2021/12/03
- [PATCH 14/14] do not apply: nbd/server: Send 64-bit hole chunk, Eric Blake, 2021/12/03
- [libnbd PATCH 00/13] libnbd patches for NBD_OPT_EXTENDED_HEADERS, Eric Blake, 2021/12/03