Re: [PATCH v3 4/5] ext4: fix possible null-ptr-deref in extents_kunit_exit()

[Ritesh Harjani (IBM) <ritesh.list@gmail.com>]

Ye Bin <yebin@huaweicloud.com> writes:

> From: Ye Bin <yebin10@huawei.com>
>
> There's issue as follows:
> KASAN: null-ptr-deref in range [0x00000000000002c0-0x00000000000002c7]
> Tainted: [E]=UNSIGNED_MODULE, [N]=TEST
> RIP: 0010:extents_kunit_exit+0x2e/0xc0 [ext4_test]
> Call Trace:
>  <TASK>
>  kunit_try_run_case_cleanup+0xbc/0x100 [kunit]
>  kunit_generic_run_threadfn_adapter+0x89/0x100 [kunit]
>  kthread+0x408/0x540
>  ret_from_fork+0xa76/0xdf0
>  ret_from_fork_asm+0x1a/0x30
>
> Above issue happens as extents_kunit_init() init testcase failed.
> So test if testcase is inited success.
>

LGTM.
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>


> Fixes: cb1e0c1d1fad ("ext4: kunit tests for extent splitting and conversion")
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>  fs/ext4/extents-test.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/extents-test.c b/fs/ext4/extents-test.c
> index 543236a31e13..6ae72986ca9c 100644
> --- a/fs/ext4/extents-test.c
> +++ b/fs/ext4/extents-test.c
> @@ -142,9 +142,12 @@ static struct file_system_type ext_fs_type = {
>  
>  static void extents_kunit_exit(struct kunit *test)
>  {
> -	struct super_block *sb = k_ctx.k_ei->vfs_inode.i_sb;
> -	struct ext4_sb_info *sbi = sb->s_fs_info;
> +	struct ext4_sb_info *sbi;
>  
> +	if (!k_ctx.k_ei)
> +		return;
> +
> +	sbi = k_ctx.k_ei->vfs_inode.i_sb->s_fs_info;
>  	ext4_es_unregister_shrinker(sbi);
>  	deactivate_super(sbi->s_sb);
>  	kfree(sbi);
> -- 
> 2.34.1