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nfsd: stricter decoding of write-like NFSv2/v3 ops (CVE-2017-7895)

This commit is contained in:
Salvatore Bonaccorso 2017-04-29 22:02:01 +02:00
parent 7961205000
commit 7ba1afb386
3 changed files with 65 additions and 0 deletions
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1
debian/changelog vendored
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@ -375,6 +375,7 @@ linux (4.9.25-1) UNRELEASED; urgency=medium
* macsec: dynamically allocate space for sglist
* nfsd: check for oversized NFSv2/v3 arguments (CVE-2017-7645)
* nfsd4: minor NFSv2/v3 write decoding cleanup
* nfsd: stricter decoding of write-like NFSv2/v3 ops (CVE-2017-7895)
[ Aurelien Jarno ]
* [mips*/octeon] Drop obsolete patch adding support for the UBNT E200

63
debian/patches/bugfix/all/nfsd-stricter-decoding-of-write-like-NFSv2-v3-ops.patch vendored Normal file
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@ -0,0 +1,63 @@
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Fri, 21 Apr 2017 15:26:30 -0400
Subject: nfsd: stricter decoding of write-like NFSv2/v3 ops
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Origin: https://git.kernel.org/linus/13bf9fbff0e5e099e2b6f003a0ab8ae145436309
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-7895
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>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
fs/nfsd/nfs3xdr.c | 4 ++++
fs/nfsd/nfsxdr.c | 2 ++
2 files changed, 6 insertions(+)
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index d18cfdd..4523346 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -369,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
args->count = ntohl(*p++);
args->stable = ntohl(*p++);
len = args->len = ntohl(*p++);
+ if ((void *)p > head->iov_base + head->iov_len)
+ return 0;
/*
* The count must equal the amount of data passed.
*/
@@ -472,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
/* first copy and check from the first page */
old = (char*)p;
vec = &rqstp->rq_arg.head[0];
+ if ((void *)old > vec->iov_base + vec->iov_len)
+ return 0;
avail = vec->iov_len - (old - (char*)vec->iov_base);
while (len && avail && *old) {
*new++ = *old++;
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 59bd88a..de07ff6 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
* bytes.
*/
hdr = (void*)p - head->iov_base;
+ if (hdr > head->iov_len)
+ return 0;
dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
/*
--
2.1.4

1
debian/patches/series vendored
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@ -112,6 +112,7 @@ bugfix/all/macsec-avoid-heap-overflow-in-skb_to_sgvec.patch
bugfix/all/macsec-dynamically-allocate-space-for-sglist.patch
bugfix/all/nfsd-check-for-oversized-NFSv2-v3-arguments.patch
bugfix/all/nfsd4-minor-NFSv2-v3-write-decoding-cleanup.patch
bugfix/all/nfsd-stricter-decoding-of-write-like-NFSv2-v3-ops.patch
# Fix exported symbol versions
bugfix/ia64/revert-ia64-move-exports-to-definitions.patch