From ac3d8fba0618c9f68832ea9fc6fe6615bda4de8d Mon Sep 17 00:00:00 2001 From: Chandan Rajendra Date: Mon, 14 Nov 2016 21:26:26 -0500 Subject: [PATCH] ext4: fix stack memory corruption with 64k block size commit 30a9d7afe70ed6bd9191d3000e2ef1a34fb58493 upstream. 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. Fixes: c9de560ded61f Signed-off-by: Chandan Rajendra Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- 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 a7a1b676b934..83ed61a6cfcb 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2222,7 +2222,7 @@ 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--; -- 2.20.1