This is a note to let you know that I've just added the patch titled ext4: fix loff_t overflow in ext4_max_bitmap_size() to the 5.10-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: ext4-fix-loff_t-overflow-in-ext4_max_bitmap_size.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 75ca6ad408f459f00b09a64f04c774559848c097 Mon Sep 17 00:00:00 2001 From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> Date: Sat, 5 Jun 2021 10:39:32 +0530 Subject: ext4: fix loff_t overflow in ext4_max_bitmap_size() From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> commit 75ca6ad408f459f00b09a64f04c774559848c097 upstream. We should use unsigned long long rather than loff_t to avoid overflow in ext4_max_bitmap_size() for comparison before returning. w/o this patch sbi->s_bitmap_maxbytes was becoming a negative value due to overflow of upper_limit (with has_huge_files as true) Below is a quick test to trigger it on a 64KB pagesize system. sudo mkfs.ext4 -b 65536 -O ^has_extents,^64bit /dev/loop2 sudo mount /dev/loop2 /mnt sudo echo "hello" > /mnt/hello -> This will error out with "echo: write error: File too large" Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Cc: stable@xxxxxxxxxx Link: https://lore.kernel.org/r/594f409e2c543e90fd836b78188dfa5c575065ba.1622867594.git.riteshh@xxxxxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/super.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3194,17 +3194,17 @@ static loff_t ext4_max_size(int blkbits, */ static loff_t ext4_max_bitmap_size(int bits, int has_huge_files) { - loff_t res = EXT4_NDIR_BLOCKS; + unsigned long long upper_limit, res = EXT4_NDIR_BLOCKS; int meta_blocks; - loff_t upper_limit; - /* This is calculated to be the largest file size for a dense, block + + /* + * This is calculated to be the largest file size for a dense, block * mapped file such that the file's total number of 512-byte sectors, * including data and all indirect blocks, does not exceed (2^48 - 1). * * __u32 i_blocks_lo and _u16 i_blocks_high represent the total * number of 512-byte sectors of the file. */ - if (!has_huge_files) { /* * !has_huge_files or implies that the inode i_block field @@ -3247,7 +3247,7 @@ static loff_t ext4_max_bitmap_size(int b if (res > MAX_LFS_FILESIZE) res = MAX_LFS_FILESIZE; - return res; + return (loff_t)res; } static ext4_fsblk_t descriptor_loc(struct super_block *sb, Patches currently in stable-queue which might be from riteshh@xxxxxxxxxxxxx are queue-5.10/ext4-fix-loff_t-overflow-in-ext4_max_bitmap_size.patch