On Sun 12-04-20 14:54:35, Ritesh Harjani wrote:
> EXT4_MAX_LOGICAL_BLOCK - map.m_lblk + 1 in case when
> map.m_lblk (offset) is 0 could overflow an unsigned int
> and become 0.
>
> Fix this.
>
> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
> Reported-by: syzbot+77fa5bdb65cc39711820@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework")
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/inode.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index e416096fc081..d630ec7a9c8e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3424,6 +3424,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> int ret;
> struct ext4_map_blocks map;
> u8 blkbits = inode->i_blkbits;
> + loff_t len;
>
> if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
> return -EINVAL;
> @@ -3435,8 +3436,11 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> * Calculate the first and last logical blocks respectively.
> */
> map.m_lblk = offset >> blkbits;
> - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
> + len = min_t(loff_t, (offset + length - 1) >> blkbits,
> EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
> + if (len > EXT4_MAX_LOGICAL_BLOCK)
> + len = EXT4_MAX_LOGICAL_BLOCK;
> + map.m_len = len;
>
> if (flags & IOMAP_WRITE)
> ret = ext4_iomap_alloc(inode, &map, flags);
> @@ -3524,6 +3528,7 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
> bool delalloc = false;
> struct ext4_map_blocks map;
> u8 blkbits = inode->i_blkbits;
> + loff_t len
>
> if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
> return -EINVAL;
> @@ -3541,8 +3546,11 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
> * Calculate the first and last logical block respectively.
> */
> map.m_lblk = offset >> blkbits;
> - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
> + len = min_t(loff_t, (offset + length - 1) >> blkbits,
> EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
> + if (len > EXT4_MAX_LOGICAL_BLOCK)
> + len = EXT4_MAX_LOGICAL_BLOCK;
> + map.m_len = len;
>
> /*
> * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
> --
> 2.21.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
