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Commit 30a9d7af authored by Chandan Rajendra's avatar Chandan Rajendra Committed by Theodore Ts'o
Browse files

ext4: fix stack memory corruption with 64k block size 



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: c9de560d
Signed-off-by: default avatarChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
parent 69e43e8c

fs/ext4/mballoc.c

+1 −1
Original line number Diff line number Diff line
@@ -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--;