mainline inclusion from mainline-v6.8-rc3 commit c9b528c35795b711331ed36dc3dbee90d5812d4e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I93HD9 CVE: CVE-2024-26601

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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This mostly reverts commit 6bd97bf273bd ("ext4: remove redundant mb_regenerate_buddy()") and reintroduces mb_regenerate_buddy(). Based on code in mb_free_blocks(), fast commit replay can end up marking as free blocks that are already marked as such. This causes corruption of the buddy bitmap so we need to regenerate it in that case.

Reported-by: Jan Kara jack@suse.cz Fixes: 6bd97bf273bd ("ext4: remove redundant mb_regenerate_buddy()") Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20240104142040.2835097-4-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Baokun Li libaokun1@huawei.com --- fs/ext4/mballoc.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index a7b8558c0d09..bbb2410a0724 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1232,6 +1232,24 @@ void ext4_mb_generate_buddy(struct super_block *sb, atomic64_add(period, &sbi->s_mb_generation_time); }

+static void mb_regenerate_buddy(struct ext4_buddy *e4b) +{ + int count; + int order = 1; + void *buddy; + + while ((buddy = mb_find_buddy(e4b, order++, &count))) + mb_set_bits(buddy, 0, count); + + e4b->bd_info->bb_fragments = 0; + memset(e4b->bd_info->bb_counters, 0, + sizeof(*e4b->bd_info->bb_counters) * + (e4b->bd_sb->s_blocksize_bits + 2)); + + ext4_mb_generate_buddy(e4b->bd_sb, e4b->bd_buddy, + e4b->bd_bitmap, e4b->bd_group, e4b->bd_info); +} + /* The buddy information is attached the buddy cache inode * for convenience. The information regarding each group * is loaded via ext4_mb_load_buddy. The information involve @@ -1920,6 +1938,8 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b, ext4_mark_group_bitmap_corrupted( sb, e4b->bd_group, EXT4_GROUP_INFO_BBITMAP_CORRUPT); + } else { + mb_regenerate_buddy(e4b); } goto done; }