| Message ID | 1635777273-46028-1-git-send-email-huangguobin4@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [-next] bonding: Fix a use-after-free problem when bond_sysfs_slave_add() failed | expand |
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) >
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) >
On 02.11.21 03:55, huangguobin wrote: > 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. [please don't top-post] The suggestion was to use sysfs_create_files(), which would handle such rollback internally. There was no mention of using bond_sysfs_slave_del(). ie. something like the following (untested): diff --git a/drivers/net/bonding/bond_sysfs_slave.c b/drivers/net/bonding/bond_sysfs_slave.c index fd07561da034..a1fd4bc0b0d2 100644 --- a/drivers/net/bonding/bond_sysfs_slave.c +++ b/drivers/net/bonding/bond_sysfs_slave.c @@ -108,15 +108,15 @@ static ssize_t ad_partner_oper_port_state_show(struct slave *slave, char *buf) } static SLAVE_ATTR_RO(ad_partner_oper_port_state); -static const struct slave_attribute *slave_attrs[] = { - &slave_attr_state, - &slave_attr_mii_status, - &slave_attr_link_failure_count, - &slave_attr_perm_hwaddr, - &slave_attr_queue_id, - &slave_attr_ad_aggregator_id, - &slave_attr_ad_actor_oper_port_state, - &slave_attr_ad_partner_oper_port_state, +static const struct attribute *slave_attrs[] = { + &slave_attr_state.attr, + &slave_attr_mii_status.attr, + &slave_attr_link_failure_count.attr, + &slave_attr_perm_hwaddr.attr, + &slave_attr_queue_id.attr, + &slave_attr_ad_aggregator_id.attr, + &slave_attr_ad_actor_oper_port_state.attr, + &slave_attr_ad_partner_oper_port_state.attr, NULL }; @@ -137,24 +137,16 @@ const struct sysfs_ops slave_sysfs_ops = { int bond_sysfs_slave_add(struct slave *slave) { - const struct slave_attribute **a; int err; - for (a = slave_attrs; *a; ++a) { - err = sysfs_create_file(&slave->kobj, &((*a)->attr)); - if (err) { - kobject_put(&slave->kobj); - return err; - } - } + err = sysfs_create_files(&slave->kobj, slave_attrs); + if (err) + kobject_put(&slave->kobj); - return 0; + return err; } void bond_sysfs_slave_del(struct slave *slave) { - const struct slave_attribute **a; - - for (a = slave_attrs; *a; ++a) - sysfs_remove_file(&slave->kobj, &((*a)->attr)); + sysfs_remove_files(&slave->kobj, slave_attrs); } > -----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) >> >
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; } void bond_sysfs_slave_del(struct slave *slave)