Re: [PATCH -next 2/2] kobject: fix memory leak when kobject_add_varg() returns error

[Greg KH]

On Wed, Sep 25, 2024 at 08:07:47PM +0800, Gaosheng Cui wrote:
> Inject fault while loading module, kobject_add_varg() may fail.
> If it fails, the kset.kobj.name allocated by kobject_set_name_vargs()
> may be leaked, the call trace as follow:
> 
> unreferenced object 0xffff8884ef4fccc0 (size 32):
>   comm "modprobe", pid 56721, jiffies 4304802933
>   backtrace (crc 4b069391):
>     [<ffffffff85e9fb2b>] kmemleak_alloc+0x4b/0x80
>     [<ffffffff83664674>] __kmalloc_node_track_caller_noprof+0x3d4/0x510
>     [<ffffffff83510656>] kstrdup+0x46/0x80
>     [<ffffffff8351070f>] kstrdup_const+0x6f/0x90
>     [<ffffffff84213842>] kvasprintf_const+0x112/0x190
>     [<ffffffff85d8446b>] kobject_set_name_vargs+0x5b/0x160
>     [<ffffffff85d85969>] kobject_init_and_add+0xc9/0x170
>     [<ffffffff83661788>] sysfs_slab_add+0x188/0x230
>     [<ffffffff83665e24>] do_kmem_cache_create+0x4d4/0x5a0
>     [<ffffffff835343cd>] __kmem_cache_create_args+0x18d/0x310
>     [<ffffffffc64a08b4>] 0xffffffffc64a08b4
>     [<ffffffffc64a005f>] 0xffffffffc64a005f
>     [<ffffffff82a04198>] do_one_initcall+0xb8/0x590
>     [<ffffffff82f0c626>] do_init_module+0x256/0x7d0
>     [<ffffffff82f12f73>] load_module+0x5953/0x7010
>     [<ffffffff82f14b0a>] init_module_from_file+0xea/0x140
> 
> To mitigate this, we need to check return value of kobject_add_internal,
> and free the name when an error is encountered.
> 
> Fixes: 244f6cee9a92 ("kobject: add kobject_add_ng function")
> Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
> ---
>  lib/kobject.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/kobject.c b/lib/kobject.c
> index ecca72622933..365e2ad12cba 100644
> --- a/lib/kobject.c
> +++ b/lib/kobject.c
> @@ -371,7 +371,13 @@ static __printf(3, 0) int kobject_add_varg(struct kobject *kobj,
>  		return retval;
>  	}
>  	kobj->parent = parent;
> -	return kobject_add_internal(kobj);
> +	retval = kobject_add_internal(kobj);
> +	if (retval) {
> +		kfree_const(kobj->name);
> +		kobj->name = NULL;
> +	}
> +
> +	return retval;
>  }
>  
>  /**
> -- 
> 2.25.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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