2011-01-24 13:42:27

by Chris Wilson

Subject: [PATCH] ext4: Fix invalid free of cache->name after ext4_mb_init() error

The name allocated for the kmem_cache was being freed in the error path even
if that name was still assigned to the newly created cache.

Cc: "Theodore Ts'o" <[email protected]>
Cc: Andreas Dilger <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
---
fs/ext4/mballoc.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 851f49b..69b90fe 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2423,7 +2423,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
int ret;
int cache_index;
struct kmem_cache *cachep;
- char *namep = NULL;

i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);

@@ -2443,7 +2442,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
cache_index = sb->s_blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
cachep = ext4_groupinfo_caches[cache_index];
if (!cachep) {
- char name[32];
+ char name[32], *namep;
int len = offsetof(struct ext4_group_info,
bb_counters[sb->s_blocksize_bits + 2]);

@@ -2459,6 +2458,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
cachep = kmem_cache_create(namep, len, 0,
SLAB_RECLAIM_ACCOUNT, NULL);
if (!cachep) {
+ kfree(namep);
ret = -ENOMEM;
goto out;
}
@@ -2520,7 +2520,6 @@ out:
if (ret) {
kfree(sbi->s_mb_offsets);
kfree(sbi->s_mb_maxs);
- kfree(namep);
}
return ret;
}
--
1.7.2.3

2011-01-24 16:25:39

by Eric Sandeen

Subject: Re: [PATCH] ext4: Fix invalid free of cache->name after ext4_mb_init() error

On 01/24/2011 07:42 AM, Chris Wilson wrote:
> The name allocated for the kmem_cache was being freed in the error path even
> if that name was still assigned to the newly created cache.

This code still has trouble on the module unload / uninit path;
I sent a more invasive patch to just use static patch names,
see [PATCH] ext4: make grpinfo slab cache names static
from last week.

-Eric

> Cc: "Theodore Ts'o" <[email protected]>
> Cc: Andreas Dilger <[email protected]>
> Signed-off-by: Chris Wilson <[email protected]>
> ---
> fs/ext4/mballoc.c | 5 ++---
> 1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 851f49b..69b90fe 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2423,7 +2423,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
> int ret;
> int cache_index;
> struct kmem_cache *cachep;
> - char *namep = NULL;
>
> i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);
>
> @@ -2443,7 +2442,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
> cache_index = sb->s_blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
> cachep = ext4_groupinfo_caches[cache_index];
> if (!cachep) {
> - char name[32];
> + char name[32], *namep;
> int len = offsetof(struct ext4_group_info,
> bb_counters[sb->s_blocksize_bits + 2]);
>
> @@ -2459,6 +2458,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
> cachep = kmem_cache_create(namep, len, 0,
> SLAB_RECLAIM_ACCOUNT, NULL);
> if (!cachep) {
> + kfree(namep);
> ret = -ENOMEM;
> goto out;
> }
> @@ -2520,7 +2520,6 @@ out:
> if (ret) {
> kfree(sbi->s_mb_offsets);
> kfree(sbi->s_mb_maxs);
> - kfree(namep);
> }
> return ret;
> }