* [PATCH V2] ext4: ext4_mb_seq_groups_show: Fix stack memory corruption
@ 2016-11-10 5:46 Chandan Rajendra
2016-11-10 17:13 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: Chandan Rajendra @ 2016-11-10 5:46 UTC (permalink / raw)
To: linux-ext4; +Cc: Chandan Rajendra, tytso, jack, adilger
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@linux.vnet.ibm.com>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH V2] ext4: ext4_mb_seq_groups_show: Fix stack memory corruption
2016-11-10 5:46 [PATCH V2] ext4: ext4_mb_seq_groups_show: Fix stack memory corruption Chandan Rajendra
@ 2016-11-10 17:13 ` Jan Kara
2016-11-15 2:35 ` Theodore Ts'o
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2016-11-10 17:13 UTC (permalink / raw)
To: Chandan Rajendra; +Cc: linux-ext4, tytso, jack, adilger
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@linux.vnet.ibm.com>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
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@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH V2] ext4: ext4_mb_seq_groups_show: Fix stack memory corruption
2016-11-10 17:13 ` Jan Kara
@ 2016-11-15 2:35 ` Theodore Ts'o
0 siblings, 0 replies; 3+ messages in thread
From: Theodore Ts'o @ 2016-11-15 2:35 UTC (permalink / raw)
To: Jan Kara; +Cc: Chandan Rajendra, linux-ext4, adilger
On Thu, Nov 10, 2016 at 06:13:46PM +0100, Jan Kara wrote:
> 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@linux.vnet.ibm.com>
>
> Looks good. You can add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
Applied, thanks!
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-11-10 5:46 [PATCH V2] ext4: ext4_mb_seq_groups_show: Fix stack memory corruption Chandan Rajendra
2016-11-10 17:13 ` Jan Kara
2016-11-15 2:35 ` Theodore Ts'o
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