From 819b23f1c501b17b9694325471789e6b5cc2d0d2 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Wed, 13 Jun 2018 23:00:48 -0400 Subject: ext4: always check block group bounds in ext4_init_block_bitmap() Regardless of whether the flex_bg feature is set, we should always check to make sure the bits we are setting in the block bitmap are within the block group bounds. https://bugzilla.kernel.org/show_bug.cgi?id=199865 Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- fs/ext4/balloc.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'fs/ext4/balloc.c') diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index b00481c475cb..8a2e202ade8a 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -184,7 +184,6 @@ static int ext4_init_block_bitmap(struct super_block *sb, unsigned int bit, bit_max; struct ext4_sb_info *sbi = EXT4_SB(sb); ext4_fsblk_t start, tmp; - int flex_bg = 0; J_ASSERT_BH(bh, buffer_locked(bh)); @@ -207,22 +206,19 @@ static int ext4_init_block_bitmap(struct super_block *sb, start = ext4_group_first_block_no(sb, block_group); - if (ext4_has_feature_flex_bg(sb)) - flex_bg = 1; - /* Set bits for block and inode bitmaps, and inode table */ tmp = ext4_block_bitmap(sb, gdp); - if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) + if (ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); tmp = ext4_inode_bitmap(sb, gdp); - if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) + if (ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); tmp = ext4_inode_table(sb, gdp); for (; tmp < ext4_inode_table(sb, gdp) + sbi->s_itb_per_group; tmp++) { - if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) + if (ext4_block_in_group(sb, tmp, block_group)) ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); } -- cgit v1.2.3 From 8844618d8aa7a9973e7b527d038a2a589665002c Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 14 Jun 2018 00:58:00 -0400 Subject: 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 Cc: stable@kernel.org --- fs/ext4/balloc.c | 11 ++++++++++- fs/ext4/ialloc.c | 14 ++++++++++++-- fs/ext4/mballoc.c | 6 ++++-- fs/ext4/super.c | 11 ++++++++++- 4 files changed, 36 insertions(+), 6 deletions(-) (limited to 'fs/ext4/balloc.c') diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index 8a2e202ade8a..e68cefe08261 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -438,7 +438,16 @@ 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 4d6e007f3569..da6c10c1e37a 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -150,7 +150,16 @@ 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); @@ -994,7 +1003,8 @@ 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 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, diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c61675d62195..4d34430d75f6 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3139,13 +3139,22 @@ 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_rdonly(sb)) + return ngroups; } return group; -- cgit v1.2.3