The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
d766f2d1e3e3 ("ext2: Add sanity checks for group and filesystem size")
d9e9866803f7 ("ext2: Adjust indentation in ext2_fill_super")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From d766f2d1e3e3bd44024a7f971ffcf8b8fbb7c5d2 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Wed, 14 Sep 2022 17:24:42 +0200
Subject: [PATCH] ext2: Add sanity checks for group and filesystem size
Add sanity check that filesystem size does not exceed the underlying
device size and that group size is big enough so that metadata can fit
into it. This avoid trying to mount some crafted filesystems with
extremely large group counts.
Reported-by: syzbot+0f2f7e65a3007d39539f@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> # Test fixup
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 252c742379cf..afb31af9302d 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1052,6 +1052,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_blocks_per_group);
goto failed_mount;
}
+ /* At least inode table, bitmaps, and sb have to fit in one group */
+ if (sbi->s_blocks_per_group <= sbi->s_itb_per_group + 3) {
+ ext2_msg(sb, KERN_ERR,
+ "error: #blocks per group smaller than metadata size: %lu <= %lu",
+ sbi->s_blocks_per_group, sbi->s_inodes_per_group + 3);
+ goto failed_mount;
+ }
if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
ext2_msg(sb, KERN_ERR,
"error: #fragments per group too big: %lu",
@@ -1065,9 +1072,14 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_inodes_per_group);
goto failed_mount;
}
+ if (sb_bdev_nr_blocks(sb) < le32_to_cpu(es->s_blocks_count)) {
+ ext2_msg(sb, KERN_ERR,
+ "bad geometry: block count %u exceeds size of device (%u blocks)",
+ le32_to_cpu(es->s_blocks_count),
+ (unsigned)sb_bdev_nr_blocks(sb));
+ goto failed_mount;
+ }
- if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
- goto cantfind_ext2;
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;
