The following nfsd bugfix is available from
git://linux-nfs.org/~bfields/linux.git for-2.6.34
Please pull for 2.6.34. Thanks!
--b.
commit 2bc3c1179c781b359d4f2f3439cb3df72afc17fc
Author: Neil Brown <neilb@xxxxxxx>
Date: Tue Apr 20 12:16:52 2010 +1000
nfsd4: bug in read_buf
When read_buf is called to move over to the next page in the pagelist
of an NFSv4 request, it sets argp->end to essentially a random
number, certainly not an address within the page which argp->p now
points to. So subsequent calls to READ_BUF will think there is much
more than a page of spare space (the cast to u32 ensures an unsigned
comparison) so we can expect to fall off the end of the second
page.
We never encountered thsi in testing because typically the only
operations which use more than two pages are write-like operations,
which have their own decoding logic. Something like a getattr after a
write may cross a page boundary, but it would be very unusual for it to
cross another boundary after that.
Cc: stable@xxxxxxxxxx
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index e170317..34ccf81 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -161,10 +161,10 @@ static __be32 *read_buf(struct nfsd4_compoundargs *argp, u32 nbytes)
argp->p = page_address(argp->pagelist[0]);
argp->pagelist++;
if (argp->pagelen < PAGE_SIZE) {
- argp->end = p + (argp->pagelen>>2);
+ argp->end = argp->p + (argp->pagelen>>2);
argp->pagelen = 0;
} else {
- argp->end = p + (PAGE_SIZE>>2);
+ argp->end = argp->p + (PAGE_SIZE>>2);
argp->pagelen -= PAGE_SIZE;
}
memcpy(((char*)p)+avail, argp->p, (nbytes - avail));
@@ -1426,10 +1426,10 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
argp->p = page_address(argp->pagelist[0]);
argp->pagelist++;
if (argp->pagelen < PAGE_SIZE) {
- argp->end = p + (argp->pagelen>>2);
+ argp->end = argp->p + (argp->pagelen>>2);
argp->pagelen = 0;
} else {
- argp->end = p + (PAGE_SIZE>>2);
+ argp->end = argp->p + (PAGE_SIZE>>2);
argp->pagelen -= PAGE_SIZE;
}
}
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