Commit b84ba662 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] ext2: fix directory handling bug

Patch from Dave Miller.  Fixes a very long-standing bug.

If a process has an fd open against a now-removed directory, lookups on that
fd will end up calling ext2_find_entry() against a zero-length directory.

When this happens ext2_find_entry() will, on the first pass through the loop,
set `kaddr' to page_address(page) - 20.  Things get confused and the "zero
length directory entry" warning triggers.

This only happens on 64-bit machines, because ext2_last_byte() is returning
an unsigned (32-bit) value, and the arithmetic works out OK for 32-bit
machines.

So we change ext2_find_entry() to bale out immediately if the directory is
zero-length.  All other directory-walking functions do this, but
ext2_find_entry() forgot to, due to the search-from-the-last-place
optimisation.
parent 5c31c779
...@@ -337,6 +337,9 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, ...@@ -337,6 +337,9 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
struct ext2_inode_info *ei = EXT2_I(dir); struct ext2_inode_info *ei = EXT2_I(dir);
ext2_dirent * de; ext2_dirent * de;
if (npages == 0)
goto out;
/* OFFSET_CACHE */ /* OFFSET_CACHE */
*res_page = NULL; *res_page = NULL;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment