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@huawei.com>
---
 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

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@huawei.com>
> ---
>  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
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
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  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
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thanks,

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