| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 40/83] ext4: fix stack memory corruption with 64k block size | Date | Wed, 4 Jan 2017 21:06:32 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Chandan Rajendra <chandan@linux.vnet.ibm.com>
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 <chandan@linux.vnet.ibm.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/ext4/mballoc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2287,7 +2287,7 @@ static int ext4_mb_seq_groups_show(struc 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--;
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