aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTheodore Ts'o <tytso@mit.edu>2018-06-14 00:58:00 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-11 16:26:44 +0200
commit5ae57329580d6ceca97559ff030a5f0e91fa66fe (patch)
tree40aa31900cec80acc95b6cfc8179d50401722b0b
parentcdde876fce2501828af33d5e4faa36c8919fc96a (diff)
ext4: only look at the bg_flags field if it is valid
commit 8844618d8aa7a9973e7b527d038a2a589665002c upstream. 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 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/ext4/balloc.c11
-rw-r--r--fs/ext4/ialloc.c14
-rw-r--r--fs/ext4/mballoc.c6
-rw-r--r--fs/ext4/super.c11
4 files changed, 36 insertions, 6 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index badb4e075225..ad13f07cf0d3 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -450,7 +450,16 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
goto verify;
}
ext4_lock_group(sb, block_group);
- 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))) {
+ if (block_group == 0) {
+ ext4_unlock_group(sb, block_group);
+ unlock_buffer(bh);
+ ext4_error(sb, "Block bitmap for bg 0 marked "
+ "uninitialized");
+ err = -EFSCORRUPTED;
+ goto out;
+ }
err = ext4_init_block_bitmap(sb, bh, block_group, desc);
set_bitmap_uptodate(bh);
set_buffer_uptodate(bh);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index dcf63daefee0..460866b2166d 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -152,7 +152,16 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
}
ext4_lock_group(sb, block_group);
- if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
+ if (ext4_has_group_desc_csum(sb) &&
+ (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT))) {
+ if (block_group == 0) {
+ ext4_unlock_group(sb, block_group);
+ unlock_buffer(bh);
+ ext4_error(sb, "Inode bitmap for bg 0 marked "
+ "uninitialized");
+ err = -EFSCORRUPTED;
+ goto out;
+ }
memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
sb->s_blocksize * 8, bh->b_data);
@@ -926,7 +935,8 @@ got:
/* recheck and clear flag under lock if we still need to */
ext4_lock_group(sb, group);
- 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, group, gdp));
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 14bd37041e1a..53e1890660a2 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 {
@@ -2969,7 +2970,8 @@ 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,
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6525127133e8..4c5d9df1790a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3023,13 +3023,22 @@ static ext4_group_t ext4_has_uninit_itable(struct super_block *sb)
ext4_group_t group, ngroups = EXT4_SB(sb)->s_groups_count;
struct ext4_group_desc *gdp = NULL;
+ if (!ext4_has_group_desc_csum(sb))
+ return ngroups;
+
for (group = 0; group < ngroups; group++) {
gdp = ext4_get_group_desc(sb, group, NULL);
if (!gdp)
continue;
- if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED)))
+ if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED))
+ continue;
+ if (group != 0)
break;
+ ext4_error(sb, "Inode table for bg 0 marked as "
+ "needing zeroing");
+ if (sb->s_flags & MS_RDONLY)
+ return ngroups;
}
return group;