Re: [reiserfs-list] major security bug in reiserfs (may affect SuSE Linux)

[Chris Mason]

On Wednesday, January 10, 2001 02:32:09 AM +0100 Marc Lehmann <[e-mail]> wrote:

>>> EIP; c013f911 <filldir+20b/221>   <=====
> Trace; c013f706 <filldir+0/221>
> Trace; c0136e01 <reiserfs_getblk+2a/16d>

The buffer reiserfs is sending to filldir is big enough for
the huge file name, so I think the real fix should be done in VFSland.

But, in the interest of providing a quick, obviously correct fix, this
reiserfs only patch will refuse to create file names larger 
than 255 chars, and skip over any directory entries larger than 
255 chars.

--- linux/include/linux/reiserfs_fs.h.1	Tue Jan  9 21:56:18 2001
+++ linux/include/linux/reiserfs_fs.h	Tue Jan  9 21:56:33 2001
@@ -467,7 +467,7 @@
 /* name by bh, ih and entry_num */
 #define B_I_E_NAME(entry_num,bh,ih) ((char *)(bh->b_data + ih->ih_item_location + (B_I_DEH(bh,ih)+(entry_num))->deh_location))
 
-#define REISERFS_MAX_NAME_LEN(block_size) (block_size - BLKH_SIZE - IH_SIZE - DEH_SIZE)	/* -SD_SIZE when entry will contain stat data */
+#define REISERFS_MAX_NAME_LEN(block_size) 255
 
 /* this structure is used for operations on directory entries. It is not a disk structure. */
 /* When reiserfs_find_entry or search_by_entry_key find directory entry, they return filled reiserfs_dir_entry structure */
--- linux/fs/reiserfs/dir.c.1	Tue Jan  9 22:06:06 2001
+++ linux/fs/reiserfs/dir.c	Tue Jan  9 22:15:17 2001
@@ -159,6 +159,10 @@
 		d_name = B_I_DEH_ENTRY_FILE_NAME (bh, ih, deh);
 		d_off = deh->deh_offset;
 		d_ino = deh->deh_objectid;
+		if (d_reclen > REISERFS_MAX_NAME_LEN(inode->i_sb->s_blocksize)){
+		    /* it is too big to send back to VFS */
+		    continue ;
+		}
 		if (d_reclen <= 32) {
 		    local_buf = small_buf ;
 		} else {