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| author | Theodore Ts'o <tytso@mit.edu> | 2018-06-14 06:58:00 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2018-06-14 06:58:00 +0200 |
| commit | 8844618d8aa7a9973e7b527d038a2a589665002c (patch) | |
| tree | 73e3eeb52d03d548d6cab2c600984f07a72b9e10 /fs/ext4/mballoc.c | |
| parent | ext4: make sure bitmaps and the inode table don't overlap with bg descriptors (diff) | |
| download | linux-8844618d8aa7a9973e7b527d038a2a589665002c.tar.xz linux-8844618d8aa7a9973e7b527d038a2a589665002c.zip | |
ext4: only look at the bg_flags field if it is valid
The bg_flags field in the block group descripts is only valid if the
uninit_bg or metadata_csum feature is enabled. We were not
consistently looking at this field; fix this.
Also block group #0 must never have uninitialized allocation bitmaps,
or need to be zeroed, since that's where the root inode, and other
special inodes are set up. Check for these conditions and mark the
file system as corrupted if they are detected.
This addresses CVE-2018-10876.
https://bugzilla.kernel.org/show_bug.cgi?id=199403
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4/mballoc.c')
| -rw-r--r-- | fs/ext4/mballoc.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 243c42fdc155..402c769c51ea 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2444,7 +2444,8 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group, * initialize bb_free to be able to skip * empty groups without initialization */ - if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { + if (ext4_has_group_desc_csum(sb) && + (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { meta_group_info[i]->bb_free = ext4_free_clusters_after_init(sb, group, desc); } else { @@ -3010,7 +3011,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, #endif ext4_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len); - if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { + if (ext4_has_group_desc_csum(sb) && + (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT); ext4_free_group_clusters_set(sb, gdp, ext4_free_clusters_after_init(sb, |