linux-ext4 - [PATCH] tune2fs: fix a NULL dereference on failed journal replay

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Date:   Fri, 23 Sep 2022 15:27:35 +0200
From:   Lubomir Rintel <lkundrak@...sk>
To:     Theodore Ts'o <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org, Lubomir Rintel <lkundrak@...sk>
Subject: [PATCH] tune2fs: fix a NULL dereference on failed journal replay

Got a crash:

  Starting program: e2fsprogs-1.46.5/misc/tune2fs -O ^has_journal -ff /dev/sdh2
  tune2fs 1.46.5 (30-Dec-2021)
  Recovering journal.
  tune2fs: Unknown code ____ 251 while recovering journal.
  Please run e2fsck -fy /dev/sdh2.

  Program received signal SIGSEGV, Segmentation fault.
  0x00007ffff7f8565a in ext2fs_mmp_stop (fs=0x0) at ../mmp.c:405
  405		if (!ext2fs_has_feature_mmp(fs->super) ||
  (gdb) bt
  #0  0x00007ffff7f8565a in ext2fs_mmp_stop (fs=0x0) at ../mmp.c:405
  #1  0x000055555555acd8 in main (argc=<optimized out>, argv=<optimized out>) at /home/lkundrak/fedora/e2fsprogs/e2fsprogs-1.46.5/misc/tune2fs.c:3441
  (gdb)

Turns out, ext2fs_run_ext3_journal() can close fs and then fail. If that
happened, we shall not jump to closefs:, quit right away instead.

Signed-off-by: Lubomir Rintel <lkundrak@...sk>
---
 misc/tune2fs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 088f87e5..96cfd001 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -3345,7 +3345,10 @@ _("Warning: The journal is dirty. You may wish to replay the journal like:\n\n"
 				"while recovering journal.\n");
 			printf(_("Please run e2fsck -fy %s.\n"), argv[1]);
 			rc = 1;
-			goto closefs;
+			if (fs)
+				goto closefs;
+			else
+				return 1;
 		}
 		sb = fs->super;
 	}
-- 
2.37.3