Hi Dan,

On 9/27/13 7:21 AM, Dan Carpenter wrote:

I have looked at this again, and I still worry that it looks like a bug.
(remote security related blah blah blah).

regards,
dan carpenter

On Mon, Feb 20, 2012 at 12:50:19PM +0300, Dan Carpenter wrote:

quoted

I had a couple questions about some map_read_chunks().

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

    150          ch_bytes = ntohl(ch->rc_target.rs_length);
                 ^^^^^^^^
It look like this is 32 bits from the network?

    151          head->arg.head[0] = rqstp->rq_arg.head[0];
    152          head->arg.tail[0] = rqstp->rq_arg.tail[0];
    153          head->arg.pages = &head->pages[head->count];
    154          head->hdr_count = head->count; /* save count of hdr pages */
    155          head->arg.page_base = 0;
    156          head->arg.page_len = ch_bytes;
    157          head->arg.len = rqstp->rq_arg.len + ch_bytes;
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Can overflow.
    158          head->arg.buflen = rqstp->rq_arg.buflen + ch_bytes;

agreed.

quoted

                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Same.  I didn't follow it through to see if an overflow matters.  Does
it?

    159          head->count++;
    160          chl_map->ch[0].start = 0;
    161          while (byte_count) {
    162                  rpl_map->sge[sge_no].iov_base =
    163                          page_address(rqstp->rq_arg.pages[page_no]) + page_off;
    164                  sge_bytes = min_t(int, PAGE_SIZE-page_off, ch_bytes);
                                           ^^^
This is the wrong cast to use.  A large ch_bytes would be counted as a
negative value and get around the cap here.

True, but if we validate the wire data like we should, that's probably 
not an issue.

quoted

    165                  rpl_map->sge[sge_no].iov_len = sge_bytes;

regards,
dan carpenter

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