* [PATCH] ext4: don't kfree uninitialized s_group_info members
@ 2011-03-10 23:03 Eric Sandeen
2011-03-22 1:27 ` Ted Ts'o
0 siblings, 1 reply; 2+ messages in thread
From: Eric Sandeen @ 2011-03-10 23:03 UTC (permalink / raw)
To: ext4 development; +Cc: dame_eugene
Per kernel.org bugzilla #30872 we may call kfree on uninitialized
members of the s_group_info array. We can avoid this by kzalloc'ing
the array, and only freeing them on the error path if they are
non-zero.
This doesn't entirely solve the oops on mount if we fail down this
path; failed_mount4: frees the sbi, for one, which gets referenced
later in the failed mount paths - I haven't worked that out yet.
Reported-by: Eugene A. Shatokhin <dame_eugene@mail.ru>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d1fe09a..e56befe 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2381,7 +2381,7 @@ static int ext4_mb_init_backend(struct super_block *sb)
/* An 8TB filesystem with 64-bit pointers requires a 4096 byte
* kmalloc. A 128kb malloc should suffice for a 256TB filesystem.
* So a two level scheme suffices for now. */
- sbi->s_group_info = kmalloc(array_size, GFP_KERNEL);
+ sbi->s_group_info = kzalloc(array_size, GFP_KERNEL);
if (sbi->s_group_info == NULL) {
printk(KERN_ERR "EXT4-fs: can't allocate buddy meta group\n");
return -ENOMEM;
@@ -2412,7 +2412,8 @@ err_freebuddy:
kmem_cache_free(cachep, ext4_get_group_info(sb, i));
i = num_meta_group_infos;
while (i-- > 0)
- kfree(sbi->s_group_info[i]);
+ if (sbi->s_group_info[i])
+ kfree(sbi->s_group_info[i]);
iput(sbi->s_buddy_cache);
err_freesgi:
kfree(sbi->s_group_info);
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ext4: don't kfree uninitialized s_group_info members
2011-03-10 23:03 [PATCH] ext4: don't kfree uninitialized s_group_info members Eric Sandeen
@ 2011-03-22 1:27 ` Ted Ts'o
0 siblings, 0 replies; 2+ messages in thread
From: Ted Ts'o @ 2011-03-22 1:27 UTC (permalink / raw)
To: Eric Sandeen; +Cc: ext4 development, dame_eugene
On Thu, Mar 10, 2011 at 05:03:15PM -0600, Eric Sandeen wrote:
> Per kernel.org bugzilla #30872 we may call kfree on uninitialized
> members of the s_group_info array. We can avoid this by kzalloc'ing
> the array, and only freeing them on the error path if they are
> non-zero.
>
> This doesn't entirely solve the oops on mount if we fail down this
> path; failed_mount4: frees the sbi, for one, which gets referenced
> later in the failed mount paths - I haven't worked that out yet.
>
> Reported-by: Eugene A. Shatokhin <dame_eugene@mail.ru>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Added to the ext4 patch tree, although I've dropped the second patch
hunk, since it's OK to call kfree on a NULL pointers:
> @@ -2412,7 +2412,8 @@ err_freebuddy:
> kmem_cache_free(cachep, ext4_get_group_info(sb, i));
> i = num_meta_group_infos;
> while (i-- > 0)
> - kfree(sbi->s_group_info[i]);
> + if (sbi->s_group_info[i])
> + kfree(sbi->s_group_info[i]);
> iput(sbi->s_buddy_cache);
> err_freesgi:
> kfree(sbi->s_group_info);
- Ted
^ permalink raw reply [flat|nested] 2+ messages in thread
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