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pNFS/flexfiles: fix incorrect size check in decode_nfs_fh()

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[ Upstream commit ed34695e15aba74f45247f1ee2cf7e09d449f925 ]

We (adam zabrocki, alexander matrosov, alexander tereshkin, maksym
bazalii) observed the check:

	if (fh->size > sizeof(struct nfs_fh))

should not use the size of the nfs_fh struct which includes an extra two
bytes from the size field.

struct nfs_fh {
	unsigned short         size;
	unsigned char          data[NFS_MAXFHSIZE];
}

but should determine the size from data[NFS_MAXFHSIZE] so the memcpy
will not write 2 bytes beyond destination.  The proposed fix is to
compare against the NFS_MAXFHSIZE directly, as is done elsewhere in fs
code base.

Fixes: d67ae825a59d ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Nikola Livic <nlivic@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Nikola Livic 2021-03-29 11:56:49 +03:00 committed by Greg Kroah-Hartman
parent fd65cac30d
commit 1fbea60ea6
1 changed files with 1 additions and 1 deletions
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2
fs/nfs/flexfilelayout/flexfilelayout.c
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@ -106,7 +106,7 @@ static int decode_nfs_fh(struct xdr_stream *xdr, struct nfs_fh *fh)
if (unlikely(!p))
return -ENOBUFS;
fh->size = be32_to_cpup(p++);
if (fh->size > sizeof(struct nfs_fh)) {
if (fh->size > NFS_MAXFHSIZE) {
printk(KERN_ERR "NFS flexfiles: Too big fh received %d\n",
fh->size);
return -EOVERFLOW;