[patch] 0001-e2fsck-fix-.-directory-repair-on-big-endian-systems.patch

0001-e2fsck-fix-.-directory-repair-on-big-endian-systems.patch (text/plain), 1.78 KB, created by Sergei Trofimovich (RETIRED) on 2021-07-30 18:58:24 UTC

From 3568d9297dccd7dcff9d46648a2239064c013574 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <[e-mail]>
Date: Fri, 30 Jul 2021 19:44:26 +0100
Subject: [PATCH] e2fsck: fix '..' directory repair on big-endian systems

The bug is initially observed on hppa and sparc by Rolf Eike Beer
where `f_baddotdir` test failed cimplaining about invalid ".."
directly after repair.

It's a regression bisected down to 63f44aaf ("e2fsck: fix ".." more
gracefully if possible ").

The bug happens in check_dot() where repair splits one on-disk dirent
into two:

    | dirent "." | <overlapped dirent ".."> | ... more ...
    | dirent "." | dirent ".." | ... more ... |

The problem is that newly creted ".." dirent is in on-disk little-endian
format as ext2fs_read_dir_block4() only accounted for oversized "." dirent.

The change explicitly flips bytes around for dirent "..".

Tested on powerpc-unknown-linux-gnu.

Reported-by: Rolf Eike Beer
Bug: https://bugs.gentoo.org/790191
Bug: https://github.com/tytso/e2fsprogs/issues/75
Fixes: 63f44aaf ("e2fsck: fix ".." more gracefully if possible ")
Signed-off-by: Sergei Trofimovich <[e-mail]>
---
 e2fsck/pass2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index f00cb40e..48a37872 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -447,6 +447,12 @@ static int check_dot(e2fsck_t ctx,
 				nextdir = (struct ext2_dir_entry *)
 					((char *) dirent + 12);
 				dirent->rec_len = 12;
+#ifdef WORDS_BIGENDIAN
+				/* We discover new on disk dir entry.
+				 * Account for it's endianness. */
+				ext2fs_dirent_swab_in2(ctx->fs,
+					nextdir, new_len, 0);
+#endif
 				/* if the next entry looks like "..", leave it
 				 * and let check_dotdot() verify the dirent,
 				 * otherwise zap the following entry. */
-- 
2.32.0