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svcrdma: Improve Reply chunk sanity checking

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Identify malformed transport headers and unsupported chunk
combinations as early as possible.

- Ensure that segment lengths are not crazy.

- Ensure that the Reply chunk's segment count is not crazy.

With a 1KB inline threshold, the largest number of Write segments
that can be conveyed is about 60 (for a RDMA_NOMSG Reply message).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever 2017-06-23 17:18:00 -04:00 committed by J. Bruce Fields
parent 3c22f32607
commit ca5c76aba7
1 changed files with 11 additions and 6 deletions
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17
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
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@ -217,15 +217,20 @@ static __be32 *xdr_check_write_list(__be32 *p, const __be32 *end)
return p; return p;
} }
static __be32 *xdr_check_reply_chunk(__be32 *p, __be32 *end) /* Sanity check the Reply chunk.
*
* Sanity checks:
* - Reply chunk does not overflow buffer.
* - Segment size limited by largest NFS data payload.
*
* Returns pointer to the following RPC header.
*/
static __be32 *xdr_check_reply_chunk(__be32 *p, const __be32 *end)
{ {
__be32 *next;
if (*p++ != xdr_zero) { if (*p++ != xdr_zero) {
next = p + 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz; p = xdr_check_write_chunk(p, end, MAX_BYTES_SPECIAL_SEG);
if (next > end) if (!p)
return NULL; return NULL;
p = next;
} }
return p; return p;
} }