fs/9p: setrlimit fix for 9p write

Current 9p client file write code does not check for RLIMIT_FSIZE resource.
This bug was found by running LTP test case for setrlimit. This bug is fixed
by calling generic_write_checks before sending the write request to the
server.
Without this patch: the write function is allowed to write above the
RLIMIT_FSIZE set by user.
With this patch: the write function checks for RLIMIT_SIZE and writes upto
the size limit.

Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index e97c92bd6f16..89c44e92022c 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -219,7 +219,9 @@ static ssize_t
 v9fs_file_write(struct file *filp, const char __user * data,
                 size_t count, loff_t * offset)
 {
-        int n, rsize, total = 0;
+        ssize_t retval;
+        size_t total = 0;
+        int n, rsize;
         struct p9_fid *fid;
         struct p9_client *clnt;
         struct inode *inode = filp->f_path.dentry->d_inode;
@@ -234,6 +236,17 @@ v9fs_file_write(struct file *filp, const char __user * data,
 
         rsize = fid->iounit ? fid->iounit : clnt->msize - P9_IOHDRSZ;
 
+        retval = generic_write_checks(filp, &origin, &count, 0);
+        if (retval)
+                goto out;
+
+        retval = -EINVAL;
+        if ((ssize_t) count < 0)
+                goto out;
+        retval = 0;
+        if (!count)
+                goto out;
+
         do {
                 if (count < rsize)
                         rsize = count;
@@ -258,9 +271,11 @@ v9fs_file_write(struct file *filp, const char __user * data,
         }
 
         if (n < 0)
-                return n;
-
-        return total;
+                retval = n;
+        else
+                retval = total;
+out:
+        return retval;
 }
 
 static int v9fs_file_fsync(struct file *filp, int datasync)