Avoid beyond bounds copy while caching ACL

When attempting to cache ACLs returned from the server, if the bitmap
size + the ACL size is greater than a PAGE_SIZE but the ACL size itself
is smaller than a PAGE_SIZE, we can read past the buffer page boundary.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reported-by: Jian Li <jiali@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 6 insertions, 8 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f5f125fdae1b..2ce069880d6b 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3628,16 +3628,16 @@ out:
         return ret;
 }
 
-static void nfs4_write_cached_acl(struct inode *inode, const char *buf, size_t acl_len)
+static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size_t pgbase, size_t acl_len)
 {
         struct nfs4_cached_acl *acl;
 
-        if (buf && acl_len <= PAGE_SIZE) {
+        if (pages && acl_len <= PAGE_SIZE) {
                 acl = kmalloc(sizeof(*acl) + acl_len, GFP_KERNEL);
                 if (acl == NULL)
                         goto out;
                 acl->cached = 1;
-                memcpy(acl->data, buf, acl_len);
+                _copy_from_pages(acl->data, pages, pgbase, acl_len);
         } else {
                 acl = kmalloc(sizeof(*acl), GFP_KERNEL);
                 if (acl == NULL)
@@ -3670,7 +3670,6 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
         struct nfs_getaclres res = {
                 .acl_len = buflen,
         };
-        void *resp_buf;
         struct rpc_message msg = {
                 .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETACL],
                 .rpc_argp = &args,
@@ -3705,7 +3704,6 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
          * the page we send as a guess */
         if (buf == NULL)
                 res.acl_flags |= NFS4_ACL_LEN_REQUEST;
-        resp_buf = page_address(pages[0]);
 
         dprintk("%s  buf %p buflen %zu npages %d args.acl_len %zu\n",
                 __func__, buf, buflen, npages, args.acl_len);
@@ -3716,9 +3714,9 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu
 
         acl_len = res.acl_len - res.acl_data_offset;
         if (acl_len > args.acl_len)
-                nfs4_write_cached_acl(inode, NULL, acl_len);
+                nfs4_write_cached_acl(inode, NULL, 0, acl_len);
         else
-                nfs4_write_cached_acl(inode, resp_buf + res.acl_data_offset,
+                nfs4_write_cached_acl(inode, pages, res.acl_data_offset,
                                       acl_len);
         if (buf) {
                 ret = -ERANGE;
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 9312dd78d349..203c0967451b 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4940,7 +4940,7 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
                                 res->acl_len = attrlen;
                                 goto out;
                         }
-                        dprintk("NFS: acl reply: attrlen %zu > page_len %u\n",
+                        dprintk("NFS: acl reply: attrlen %u > page_len %zu\n",
                                         attrlen, page_len);
                         return -EINVAL;
                 }