[2/3] ext4: make sure bitmaps and the inode table don't overlap with bg descriptors

Message ID 20180614050512.18633-2-tytso@mit.edu
State Accepted, archived
Headers show
Series
  • Untitled series #50069
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Commit Message

Theodore Y. Ts'o June 14, 2018, 5:05 a.m.
It's really bad when the allocation bitmaps and the inode table
overlap with the block group descriptors, since it causes random
corruption of the bg descriptors.  So we really want to head those off
at the pass.

https://bugzilla.kernel.org/show_bug.cgi?id=199865

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/super.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

Patch

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c8b7b8302e90..c61675d62195 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2348,6 +2348,7 @@  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 block_bitmap;
 	ext4_fsblk_t inode_bitmap;
 	ext4_fsblk_t inode_table;
@@ -2380,6 +2381,14 @@  static int ext4_check_descriptors(struct super_block *sb,
 			if (!sb_rdonly(sb))
 				return 0;
 		}
+		if (block_bitmap >= sb_block + 1 &&
+		    block_bitmap <= last_bg_block) {
+			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
+				 "Block bitmap for group %u overlaps "
+				 "block group descriptors", i);
+			if (!sb_rdonly(sb))
+				return 0;
+		}
 		if (block_bitmap < first_block || block_bitmap > last_block) {
 			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
 			       "Block bitmap for group %u not in group "
@@ -2394,6 +2403,14 @@  static int ext4_check_descriptors(struct super_block *sb,
 			if (!sb_rdonly(sb))
 				return 0;
 		}
+		if (inode_bitmap >= sb_block + 1 &&
+		    inode_bitmap <= last_bg_block) {
+			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
+				 "Inode bitmap for group %u overlaps "
+				 "block group descriptors", i);
+			if (!sb_rdonly(sb))
+				return 0;
+		}
 		if (inode_bitmap < first_block || inode_bitmap > last_block) {
 			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
 			       "Inode bitmap for group %u not in group "
@@ -2408,6 +2425,14 @@  static int ext4_check_descriptors(struct super_block *sb,
 			if (!sb_rdonly(sb))
 				return 0;
 		}
+		if (inode_table >= sb_block + 1 &&
+		    inode_table <= last_bg_block) {
+			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
+				 "Inode table for group %u overlaps "
+				 "block group descriptors", i);
+			if (!sb_rdonly(sb))
+				return 0;
+		}
 		if (inode_table < first_block ||
 		    inode_table + sbi->s_itb_per_group - 1 > last_block) {
 			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "