64 lines
2.1 KiB
Diff
64 lines
2.1 KiB
Diff
From: "J. Bruce Fields" <bfields@redhat.com>
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Date: Fri, 21 Apr 2017 15:26:30 -0400
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Subject: nfsd: stricter decoding of write-like NFSv2/v3 ops
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Origin: https://git.kernel.org/linus/13bf9fbff0e5e099e2b6f003a0ab8ae145436309
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-7895
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The NFSv2/v3 code does not systematically check whether we decode past
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the end of the buffer. This generally appears to be harmless, but there
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are a few places where we do arithmetic on the pointers involved and
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don't account for the possibility that a length could be negative. Add
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checks to catch these.
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Reported-by: Tuomas Haanpää <thaan@synopsys.com>
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Reported-by: Ari Kauppi <ari@synopsys.com>
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Reviewed-by: NeilBrown <neilb@suse.com>
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Cc: stable@vger.kernel.org
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Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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---
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fs/nfsd/nfs3xdr.c | 4 ++++
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fs/nfsd/nfsxdr.c | 2 ++
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2 files changed, 6 insertions(+)
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diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
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index d18cfdd..4523346 100644
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--- a/fs/nfsd/nfs3xdr.c
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+++ b/fs/nfsd/nfs3xdr.c
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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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diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
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index 59bd88a..de07ff6 100644
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--- a/fs/nfsd/nfsxdr.c
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+++ b/fs/nfsd/nfsxdr.c
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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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--
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2.1.4
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