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SubjectRE: [PATCH -next] bonding: Fix a use-after-free problem when bond_sysfs_slave_add() failed
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I think bond_sysfs_slave_del should not be used in the error handling process, because bond_sysfs_slave_del will traverse all slave_attrs and release them. When sysfs_create_file fails, only some attributes may be created successfully.
-----Original Message-----
From: Julian Wiedmann [mailto:jwi@linux.ibm.com]
Sent: Tuesday, November 2, 2021 3:31 AM
To: huangguobin <huangguobin4@huawei.com>; j.vosburgh@gmail.com; vfalico@gmail.com; andy@greyhouse.net; davem@davemloft.net; kuba@kernel.org
Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next] bonding: Fix a use-after-free problem when bond_sysfs_slave_add() failed

On 01.11.21 15:34, Huang Guobin wrote:
> When I do fuzz test for bonding device interface, I got the following
> use-after-free Calltrace:
>

[...]

> Fixes: 7afcaec49696 (bonding: use kobject_put instead of _del after
> kobject_add)
> Signed-off-by: Huang Guobin <huangguobin4@huawei.com>
> ---
> drivers/net/bonding/bond_sysfs_slave.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_sysfs_slave.c
> b/drivers/net/bonding/bond_sysfs_slave.c
> index fd07561..d1a5b3f 100644
> --- a/drivers/net/bonding/bond_sysfs_slave.c
> +++ b/drivers/net/bonding/bond_sysfs_slave.c
> @@ -137,18 +137,23 @@ static ssize_t slave_show(struct kobject *kobj,
>
> int bond_sysfs_slave_add(struct slave *slave) {
> - const struct slave_attribute **a;
> + const struct slave_attribute **a, **b;
> int err;
>
> for (a = slave_attrs; *a; ++a) {
> err = sysfs_create_file(&slave->kobj, &((*a)->attr));
> if (err) {
> - kobject_put(&slave->kobj);
> - return err;
> + goto err_remove_file;
> }
> }
>
> return 0;
> +
> +err_remove_file:
> + for (b = slave_attrs; b < a; ++b)
> + sysfs_remove_file(&slave->kobj, &((*b)->attr));
> +
> + return err;
> }
>

This looks like a candidate for sysfs_create_files(), no?

> void bond_sysfs_slave_del(struct slave *slave)
>

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