This is a note to let you know that I've just added the patch titled
ext2: Add more validity checks for inode counts
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext2-add-more-validity-checks-for-inode-counts.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 64f8ba6d46b6e18b3dce31479b822604baa5419c
Author: Jan Kara <jack@xxxxxxx>
Date: Tue Jul 26 13:13:50 2022 +0200
ext2: Add more validity checks for inode counts
[ Upstream commit fa78f336937240d1bc598db817d638086060e7e9 ]
Add checks verifying number of inodes stored in the superblock matches
the number computed from number of inodes per group. Also verify we have
at least one block worth of inodes per group. This prevents crashes on
corrupted filesystems.
Reported-by: syzbot+d273f7d7f58afd93be48@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index ad9fd08f66ba..44a1f356aca2 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1088,9 +1088,10 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_frags_per_group);
goto failed_mount;
}
- if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
+ if (sbi->s_inodes_per_group < sbi->s_inodes_per_block ||
+ sbi->s_inodes_per_group > sb->s_blocksize * 8) {
ext2_msg(sb, KERN_ERR,
- "error: #inodes per group too big: %lu",
+ "error: invalid #inodes per group: %lu",
sbi->s_inodes_per_group);
goto failed_mount;
}
@@ -1100,6 +1101,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
le32_to_cpu(es->s_first_data_block) - 1)
/ EXT2_BLOCKS_PER_GROUP(sb)) + 1;
+ if ((u64)sbi->s_groups_count * sbi->s_inodes_per_group !=
+ le32_to_cpu(es->s_inodes_count)) {
+ ext2_msg(sb, KERN_ERR, "error: invalid #inodes: %u vs computed %llu",
+ le32_to_cpu(es->s_inodes_count),
+ (u64)sbi->s_groups_count * sbi->s_inodes_per_group);
+ goto failed_mount;
+ }
db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
EXT2_DESC_PER_BLOCK(sb);
sbi->s_group_desc = kmalloc_array (db_count,
