[PATCH] v9fs: readlink extended mode check

LANL reported some issues with random crashes during mount of legacy protocol
servers (9P2000 versus 9P2000.u) -- crash was always happening in readlink
(which should never happen in legacy mode).  Added some sanity conditionals to
the get_inode code which should prevent the errors LANL was seeing.  Code
tested benign through regression.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 30 insertions, 5 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 36fff087167f..0c13fc600049 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -44,6 +44,7 @@
 #include "fid.h"
 
 static struct inode_operations v9fs_dir_inode_operations;
+static struct inode_operations v9fs_dir_inode_operations_ext;
 static struct inode_operations v9fs_file_inode_operations;
 static struct inode_operations v9fs_symlink_inode_operations;
 
@@ -232,6 +233,7 @@ v9fs_mistat2unix(struct v9fs_stat *mistat, struct stat *buf,
 struct inode *v9fs_get_inode(struct super_block *sb, int mode)
 {
         struct inode *inode = NULL;
+        struct v9fs_session_info *v9ses = sb->s_fs_info;
 
         dprintk(DEBUG_VFS, "super block: %p mode: %o\n", sb, mode);
 
@@ -250,6 +252,10 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode)
                 case S_IFBLK:
                 case S_IFCHR:
                 case S_IFSOCK:
+                        if(!v9ses->extended) {
+                                dprintk(DEBUG_ERROR, "special files without extended mode\n");
+                                return ERR_PTR(-EINVAL);
+                        }
                         init_special_inode(inode, inode->i_mode,
                                            inode->i_rdev);
                         break;
@@ -257,14 +263,21 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode)
                         inode->i_op = &v9fs_file_inode_operations;
                         inode->i_fop = &v9fs_file_operations;
                         break;
+                case S_IFLNK:
+                        if(!v9ses->extended) {
+                                dprintk(DEBUG_ERROR, "extended modes used w/o 9P2000.u\n");
+                                return ERR_PTR(-EINVAL);
+                        }
+                        inode->i_op = &v9fs_symlink_inode_operations;
+                        break;
                 case S_IFDIR:
                         inode->i_nlink++;
-                        inode->i_op = &v9fs_dir_inode_operations;
+                        if(v9ses->extended)
+                                inode->i_op = &v9fs_dir_inode_operations_ext;
+                        else
+                                inode->i_op = &v9fs_dir_inode_operations;
                         inode->i_fop = &v9fs_dir_operations;
                         break;
-                case S_IFLNK:
-                        inode->i_op = &v9fs_symlink_inode_operations;
-                        break;
                 default:
                         dprintk(DEBUG_ERROR, "BAD mode 0x%x S_IFMT 0x%x\n",
                                 mode, mode & S_IFMT);
@@ -1284,7 +1297,7 @@ v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
         return retval;
 }
 
-static struct inode_operations v9fs_dir_inode_operations = {
+static struct inode_operations v9fs_dir_inode_operations_ext = {
         .create = v9fs_vfs_create,
         .lookup = v9fs_vfs_lookup,
         .symlink = v9fs_vfs_symlink,
@@ -1299,6 +1312,18 @@ static struct inode_operations v9fs_dir_inode_operations = {
         .setattr = v9fs_vfs_setattr,
 };
 
+static struct inode_operations v9fs_dir_inode_operations = {
+        .create = v9fs_vfs_create,
+        .lookup = v9fs_vfs_lookup,
+        .unlink = v9fs_vfs_unlink,
+        .mkdir = v9fs_vfs_mkdir,
+        .rmdir = v9fs_vfs_rmdir,
+        .mknod = v9fs_vfs_mknod,
+        .rename = v9fs_vfs_rename,
+        .getattr = v9fs_vfs_getattr,
+        .setattr = v9fs_vfs_setattr,
+};
+
 static struct inode_operations v9fs_file_inode_operations = {
         .getattr = v9fs_vfs_getattr,
         .setattr = v9fs_vfs_setattr,