On Thu 10-11-16 11:16:04, Chandan Rajendra wrote:
> The number of 'counters' elements needed in 'struct sg' is
> super_block->s_blocksize_bits + 2. Presently we have 16 'counters'
> elements in the array. This is insufficient for block sizes >= 32k. In
> such cases the memcpy operation performed in ext4_mb_seq_groups_show()
> would cause stack memory corruption.
>
> Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> Changelog:
> v1->v2: Use EXT4_MAX_BLOCK_LOG_SIZE instead of the integer constant 16.
>
> fs/ext4/mballoc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index a937ac7..7ae43c5 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2287,7 +2287,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
> struct ext4_group_info *grinfo;
> struct sg {
> struct ext4_group_info info;
> - ext4_grpblk_t counters[16];
> + ext4_grpblk_t counters[EXT4_MAX_BLOCK_LOG_SIZE + 2];
> } sg;
>
> group--;
> --
> 2.5.5
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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