nfsd: stricter decoding of write-like NFSv2/v3 ops
commit 13bf9fbff0
upstream.
The NFSv2/v3 code does not systematically check whether we decode past
the end of the buffer. This generally appears to be harmless, but there
are a few places where we do arithmetic on the pointers involved and
don't account for the possibility that a length could be negative. Add
checks to catch these.
Reported-by: Tuomas Haanpää <thaan@synopsys.com>
Reported-by: Ari Kauppi <ari@synopsys.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
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@ -369,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
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args->count = ntohl(*p++);
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args->stable = ntohl(*p++);
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len = args->len = ntohl(*p++);
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if ((void *)p > head->iov_base + head->iov_len)
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return 0;
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/*
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* The count must equal the amount of data passed.
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*/
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@ -472,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
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/* first copy and check from the first page */
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old = (char*)p;
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vec = &rqstp->rq_arg.head[0];
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if ((void *)old > vec->iov_base + vec->iov_len)
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return 0;
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avail = vec->iov_len - (old - (char*)vec->iov_base);
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while (len && avail && *old) {
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*new++ = *old++;
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@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
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* bytes.
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*/
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hdr = (void*)p - head->iov_base;
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if (hdr > head->iov_len)
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return 0;
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dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
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/*
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