[PATCH] f2fs: fix double free of unicode map

[PATCH] f2fs: fix double free of unicode map

[Hyeongseok Kim]

In case of retrying fill_super with skip_recovery,
s_encoding for casefold would not be loaded again even though it's
already been freed because it's not NULL.
Set NULL after free to prevent double freeing when unmount.

Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
---
 fs/f2fs/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 00eff2f51807..fef22e476c52 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3918,6 +3918,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 
 #ifdef CONFIG_UNICODE
 	utf8_unload(sb->s_encoding);
+	sb->s_encoding = NULL;
 #endif
 free_options:
 #ifdef CONFIG_QUOTA
-- 
2.27.0.83.g0313f36

Re: [f2fs-dev] [PATCH] f2fs: fix double free of unicode map

[Eric Biggers]

On Thu, Nov 12, 2020 at 05:02:01PM +0900, Hyeongseok Kim wrote:
> In case of retrying fill_super with skip_recovery,
> s_encoding for casefold would not be loaded again even though it's
> already been freed because it's not NULL.
> Set NULL after free to prevent double freeing when unmount.
> 
> Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
> ---
>  fs/f2fs/super.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 00eff2f51807..fef22e476c52 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -3918,6 +3918,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  
>  #ifdef CONFIG_UNICODE
>  	utf8_unload(sb->s_encoding);
> +	sb->s_encoding = NULL;
>  #endif
>  free_options:
>  #ifdef CONFIG_QUOTA
> -- 

This is:

Fixes: eca4873ee1b6 ("f2fs: Use generic casefolding support")

Right?

- Eric

Re: [f2fs-dev] [PATCH] f2fs: fix double free of unicode map

[hyeongseok]

On 11/12/20 5:17 PM, Eric Biggers wrote:
> On Thu, Nov 12, 2020 at 05:02:01PM +0900, Hyeongseok Kim wrote:
>> In case of retrying fill_super with skip_recovery,
>> s_encoding for casefold would not be loaded again even though it's
>> already been freed because it's not NULL.
>> Set NULL after free to prevent double freeing when unmount.
>>
>> Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
>> ---
>>   fs/f2fs/super.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 00eff2f51807..fef22e476c52 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -3918,6 +3918,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>>   
>>   #ifdef CONFIG_UNICODE
>>   	utf8_unload(sb->s_encoding);
>> +	sb->s_encoding = NULL;
>>   #endif
>>   free_options:
>>   #ifdef CONFIG_QUOTA
>> -- 
> This is:
>
> Fixes: eca4873ee1b6 ("f2fs: Use generic casefolding support")
>
> Right?
>
> - Eric
>
Right. Should I add "Fixes" tag and send v2?