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FAILED: patch "[PATCH] ext4: fix false negatives *and* false positives in" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 30, 2018

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Stable branch ext4 file system
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The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 44de022c4382541cebdd6de4465d1f4f465ff1dd Mon Sep 17 00:00:00 2001

From: Theodore Ts'o <[email protected]>
Date: Sun, 8 Jul 2018 19:35:02 -0400
Subject: [PATCH] ext4: fix false negatives *and* false positives in
ext4_check_descriptors()

Ext4_check_descriptors() was getting called before s_gdb_count was initialized. So for file systems w/o the meta_bg feature, allocation bitmaps could overlap the block group descriptors and ext4 wouldn't notice.

For file systems with the meta_bg feature enabled, there was a fencepost error which would cause the ext4_check_descriptors() to incorrectly believe that the block allocation bitmap overlaps with the block group descriptor blocks, and it would reject the mount.

Fix both of these problems.

Signed-off-by Theodore Ts'o <[email protected]>
Cc [email protected]
fs/ext4/super.c +2 -3
index ba2396a7bd04..eff5c983e067 100644
@@ -2342,7 +2342,7 @@ static int ext4_check_descriptors(struct super_block *sb,
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 	ext4_fsblk_t last_block;
-	ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0) + 1;
+	ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0);
 	ext4_fsblk_t block_bitmap;
 	ext4_fsblk_t inode_bitmap;
 	ext4_fsblk_t inode_table;

@@ -4085,14 +4085,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			goto failed_mount2;
 		}
 	}
+	sbi->s_gdb_count = db_count;
 	if (!ext4_check_descriptors(sb, logical_sb_block, &first_not_zeroed)) {
 		ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
 		ret = -EFSCORRUPTED;
 		goto failed_mount2;
 	}
 
-	sbi->s_gdb_count = db_count;
-
 	timer_setup(&sbi->s_err_report, print_daily_error_info, 0);
 
 	/* Register extent status tree shrinker */