ceph: avoid panic with mismatched symlink sizes in fill_inode()

Return -EINVAL rather than panic if iinfo->symlink_len and inode->i_size
do not match.

Also use kstrndup rather than kmalloc/memcpy.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Alex Elder <elder@dreamhost.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 2c489378b4cd..9fff9f3b17e4 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -677,18 +677,19 @@ static int fill_inode(struct inode *inode,
         case S_IFLNK:
                 inode->i_op = &ceph_symlink_iops;
                 if (!ci->i_symlink) {
-                        int symlen = iinfo->symlink_len;
+                        u32 symlen = iinfo->symlink_len;
                         char *sym;
 
-                        BUG_ON(symlen != inode->i_size);
                         spin_unlock(&ci->i_ceph_lock);
 
+                        err = -EINVAL;
+                        if (WARN_ON(symlen != inode->i_size))
+                                goto out;
+
                         err = -ENOMEM;
-                        sym = kmalloc(symlen+1, GFP_NOFS);
+                        sym = kstrndup(iinfo->symlink, symlen, GFP_NOFS);
                         if (!sym)
                                 goto out;
-                        memcpy(sym, iinfo->symlink, symlen);
-                        sym[symlen] = 0;
 
                         spin_lock(&ci->i_ceph_lock);
                         if (!ci->i_symlink)