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authorSachin Prabhu <sprabhu@redhat.com>2012-04-17 14:35:39 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-21 10:46:24 -0700
commit22594eea7aea374c0680f70fd89eeb1fc47ae635 (patch)
treefde98636153ccdd7539e03ccb2758c5902376c9d
parent4262cd1f4b734ea5fa05c37043c89106f38b2daa (diff)
Avoid reading past buffer when calling GETACL
commit 5a00689930ab975fdd1b37b034475017e460cf2a upstream. Bug noticed in commit bf118a342f10dafe44b14451a1392c3254629a1f When calling GETACL, if the size of the bitmap array, the length attribute and the acl returned by the server is greater than the allocated buffer(args.acl_len), we can Oops with a General Protection fault at _copy_from_pages() when we attempt to read past the pages allocated. This patch allocates an extra PAGE for the bitmap and checks to see that the bitmap + attribute_length + ACLs don't exceed the buffer space allocated to it. Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> Reported-by: Jian Li <jiali@redhat.com> [Trond: Fixed a size_t vs unsigned int printk() warning] Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/nfs/nfs4proc.c16
-rw-r--r--fs/nfs/nfs4xdr.c18
2 files changed, 21 insertions, 13 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f3919dca02b5..07c8ffc8a846 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3587,19 +3587,23 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
if (npages == 0)
npages = 1;
+ /* Add an extra page to handle the bitmap returned */
+ npages++;
+
for (i = 0; i < npages; i++) {
pages[i] = alloc_page(GFP_KERNEL);
if (!pages[i])
goto out_free;
}
- if (npages > 1) {
- /* for decoding across pages */
- res.acl_scratch = alloc_page(GFP_KERNEL);
- if (!res.acl_scratch)
- goto out_free;
- }
+
+ /* for decoding across pages */
+ res.acl_scratch = alloc_page(GFP_KERNEL);
+ if (!res.acl_scratch)
+ goto out_free;
+
args.acl_len = npages * PAGE_SIZE;
args.acl_pgbase = 0;
+
/* Let decode_getfacl know not to fail if the ACL data is larger than
* the page we send as a guess */
if (buf == NULL)
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 33bd8d0f745d..94da8675b896 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4975,11 +4975,19 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
bitmap[3] = {0};
struct kvec *iov = req->rq_rcv_buf.head;
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;
+
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;
if ((status = decode_attr_length(xdr, &attrlen, &savep)) != 0)
@@ -4989,28 +4997,24 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
return -EIO;
if (likely(bitmap[0] & FATTR4_WORD0_ACL)) {
size_t hdrlen;
- u32 recvd;
/* 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 = be32_to_cpup(bm_p) + 2;
- res->acl_data_offset <<= 2;
/* We ignore &savep and don't do consistency checks on
* the attr length. Let userspace figure it out.... */
hdrlen = (u8 *)xdr->p - (u8 *)iov->iov_base;
attrlen += res->acl_data_offset;
- recvd = req->rq_rcv_buf.len - hdrlen;
- if (attrlen > recvd) {
+ if (attrlen > 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 > recvd %u\n",
- attrlen, recvd);
+ dprintk("NFS: acl reply: attrlen %u > page_len %zu\n",
+ attrlen, page_len);
return -EINVAL;
}
xdr_read_pages(xdr, attrlen);