Patch "ext4: fix stack memory corruption with 64k block size" has been added to the 4.9-stable tree

Patch "ext4: fix stack memory corruption with 64k block size" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ext4: fix stack memory corruption with 64k block size

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-fix-stack-memory-corruption-with-64k-block-size.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 30a9d7afe70ed6bd9191d3000e2ef1a34fb58493 Mon Sep 17 00:00:00 2001
From: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Date: Mon, 14 Nov 2016 21:26:26 -0500
Subject: ext4: fix stack memory corruption with 64k block size

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--;


Patches currently in stable-queue which might be from chandan@linux.vnet.ibm.com are

queue-4.9/ext4-fix-mballoc-breakage-with-64k-block-size.patch
queue-4.9/ext4-fix-stack-memory-corruption-with-64k-block-size.patch