Re: [PATCH] ubifs: fix possible dereference after free

[Zhihao Cheng]

在 2023/9/5 18:12, Konstantin Meskhidze 写道:
> 'old_idx' could be dereferenced after free via 'rb_link_node' function
> call.
>
> Fixes: b5fda08ef213 ("ubifs: Fix memleak when insert_old_idx() failed")
> Co-developed-by: Ivanov Mikhail <ivanov.mikhail1@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>
> ---
>   fs/ubifs/tnc.c | 1 +
>   1 file changed, 1 insertion(+)

Only for static alarms，although it couldn't happen in theory.

Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>

> diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
> index 6b7d95b65f4b..f4728e65d1bd 100644
> --- a/fs/ubifs/tnc.c
> +++ b/fs/ubifs/tnc.c
> @@ -64,8 +64,9 @@ static void do_insert_old_idx(struct ubifs_info *c,
>   			p = &(*p)->rb_right;
>   		else {
>   			ubifs_err(c, "old idx added twice!");
>   			kfree(old_idx);
> +			return;
>   		}
>   	}
>   	rb_link_node(&old_idx->rb, parent, p);
>   	rb_insert_color(&old_idx->rb, &c->old_idx);