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nfsd4: fix oops on unusual readlike compound 

If the argument and reply together exceed the maximum payload size, then
a reply with a read-like operation can overlow the rq_pages array.

Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2012-12-04 18:25:10 -05:00
parent 9b3234b922
commit d5f50b0c29
1 changed files with 10 additions and 1 deletions
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11
fs/nfsd/nfs4xdr.c
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@ -2925,11 +2925,16 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
len = maxcount;
v = 0;
while (len > 0) {
pn = resp->rqstp->rq_resused++;
pn = resp->rqstp->rq_resused;
if (!resp->rqstp->rq_respages[pn]) { /* ran out of pages */
maxcount -= len;
break;
}
resp->rqstp->rq_vec[v].iov_base =
page_address(resp->rqstp->rq_respages[pn]);
resp->rqstp->rq_vec[v].iov_len =
len < PAGE_SIZE ? len : PAGE_SIZE;
resp->rqstp->rq_resused++;
v++;
len -= PAGE_SIZE;
}
@ -2975,6 +2980,8 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
return nfserr;
if (resp->xbuf->page_len)
return nfserr_resource;
if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
return nfserr_resource;
page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);
@ -3024,6 +3031,8 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
return nfserr;
if (resp->xbuf->page_len)
return nfserr_resource;
if (!resp->rqstp->rq_respages[resp->rqstp->rq_resused])
return nfserr_resource;
RESERVE_SPACE(NFS4_VERIFIER_SIZE);
savep = p;