75 lines
2.7 KiB
Diff
75 lines
2.7 KiB
Diff
From: Theodore Ts'o <tytso@mit.edu>
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Date: Wed, 13 Jun 2018 23:08:26 -0400
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Subject: ext4: make sure bitmaps and the inode table don't overlap with bg
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descriptors
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit?id=6b506a7d09854128b1da9571d879ee9dea3ffb02
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-10878
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It's really bad when the allocation bitmaps and the inode table
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overlap with the block group descriptors, since it causes random
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corruption of the bg descriptors. So we really want to head those off
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at the pass.
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https://bugzilla.kernel.org/show_bug.cgi?id=199865
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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---
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fs/ext4/super.c | 25 +++++++++++++++++++++++++
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1 file changed, 25 insertions(+)
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--- a/fs/ext4/super.c
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+++ b/fs/ext4/super.c
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@@ -2307,6 +2307,7 @@ static int ext4_check_descriptors(struct
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
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ext4_fsblk_t last_block;
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+ ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0) + 1;
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ext4_fsblk_t block_bitmap;
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ext4_fsblk_t inode_bitmap;
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ext4_fsblk_t inode_table;
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@@ -2339,6 +2340,14 @@ static int ext4_check_descriptors(struct
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if (!sb_rdonly(sb))
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return 0;
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}
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+ if (block_bitmap >= sb_block + 1 &&
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+ block_bitmap <= last_bg_block) {
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+ ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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+ "Block bitmap for group %u overlaps "
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+ "block group descriptors", i);
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+ if (!sb_rdonly(sb))
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+ return 0;
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+ }
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if (block_bitmap < first_block || block_bitmap > last_block) {
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ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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"Block bitmap for group %u not in group "
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@@ -2353,6 +2362,14 @@ static int ext4_check_descriptors(struct
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if (!sb_rdonly(sb))
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return 0;
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}
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+ if (inode_bitmap >= sb_block + 1 &&
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+ inode_bitmap <= last_bg_block) {
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+ ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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+ "Inode bitmap for group %u overlaps "
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+ "block group descriptors", i);
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+ if (!sb_rdonly(sb))
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+ return 0;
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+ }
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if (inode_bitmap < first_block || inode_bitmap > last_block) {
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ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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"Inode bitmap for group %u not in group "
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@@ -2367,6 +2384,14 @@ static int ext4_check_descriptors(struct
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if (!sb_rdonly(sb))
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return 0;
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}
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+ if (inode_table >= sb_block + 1 &&
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+ inode_table <= last_bg_block) {
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+ ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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+ "Inode table for group %u overlaps "
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+ "block group descriptors", i);
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+ if (!sb_rdonly(sb))
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+ return 0;
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+ }
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if (inode_table < first_block ||
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inode_table + sbi->s_itb_per_group - 1 > last_block) {
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ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
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