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NFSv4: Fix pointer arithmetic in decode_getacl

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Resetting the cursor xdr->p to a previous value is not a safe
practice: if the xdr_stream has crossed out of the initial iovec,
then a bunch of other fields would need to be reset too.

Fix this issue by using xdr_enter_page() so that the buffer gets
page aligned at the bitmap _before_ we decode it.

Also fix the confusion of the ACL length with the page buffer length
by not adding the base offset to the ACL length...

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Trond Myklebust 2012-08-14 17:30:10 -04:00
parent 425e776d93
commit 519d3959e3
2 changed files with 8 additions and 15 deletions
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2
fs/nfs/nfs4proc.c
View file

@ -3819,7 +3819,7 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
if (ret)
goto out_free;
acl_len = res.acl_len - res.acl_data_offset;
acl_len = res.acl_len;
if (acl_len > args.acl_len)
nfs4_write_cached_acl(inode, NULL, 0, acl_len);
else

21
fs/nfs/nfs4xdr.c
View file

@ -5049,18 +5049,14 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
uint32_t attrlen,
bitmap[3] = {0};
int status;
size_t page_len = xdr->buf->page_len;
res->acl_len = 0;
if ((status = decode_op_hdr(xdr, OP_GETATTR)) != 0)
goto out;
xdr_enter_page(xdr, xdr->buf->page_len);
bm_p = xdr->p;
res->acl_data_offset = be32_to_cpup(bm_p) + 2;
res->acl_data_offset <<= 2;
/* Check if the acl data starts beyond the allocated buffer */
if (res->acl_data_offset > page_len)
return -ERANGE;
if ((status = decode_attr_bitmap(xdr, bitmap)) != 0)
goto out;
@ -5074,23 +5070,20 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
/* The bitmap (xdr len + bitmaps) and the attr xdr len words
* are stored with the acl data to handle the problem of
* variable length bitmaps.*/
xdr->p = bm_p;
res->acl_data_offset = (xdr->p - bm_p) << 2;
/* We ignore &savep and don't do consistency checks on
* the attr length. Let userspace figure it out.... */
attrlen += res->acl_data_offset;
if (attrlen > page_len) {
res->acl_len = attrlen;
if (attrlen + res->acl_data_offset > xdr->buf->page_len) {
if (res->acl_flags & NFS4_ACL_LEN_REQUEST) {
/* getxattr interface called with a NULL buf */
res->acl_len = attrlen;
goto out;
}
dprintk("NFS: acl reply: attrlen %u > page_len %zu\n",
attrlen, page_len);
dprintk("NFS: acl reply: attrlen %u > page_len %u\n",
attrlen, xdr->buf->page_len);
return -EINVAL;
}
xdr_read_pages(xdr, attrlen);
res->acl_len = attrlen;
} else
status = -EOPNOTSUPP;