| Message ID | 20210621070058.37682-1-mie@igel.co.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Lorenzo Pieralisi |
| Headers | show |
| Series | PCI: endpoint: Fix use after free in pci_epf_remove_cfs() | expand |
On Mon, Jun 21, 2021 at 04:00:58PM +0900, Shunsuke Mie wrote: > All of entries are freed in a loop, however, the freed entry is accessed > by list_del() after the loop. > > When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() > is called, and occurred the use after free. Therefore, kernel panics > randomly after or while the module unloading. > > I tested this patch with r8a77951-Salvator-xs boards. > > Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") > Signed-off-by: Shunsuke Mie <mie@igel.co.jp> > --- > drivers/pci/endpoint/pci-epf-core.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly. </formletter>
[dropped stable, erroneously added to the CC list] On Mon, Jun 21, 2021 at 04:00:58PM +0900, Shunsuke Mie wrote: > All of entries are freed in a loop, however, the freed entry is accessed > by list_del() after the loop. > > When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() > is called, and occurred the use after free. Therefore, kernel panics > randomly after or while the module unloading. > > I tested this patch with r8a77951-Salvator-xs boards. > > Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") > Signed-off-by: Shunsuke Mie <mie@igel.co.jp> > --- > drivers/pci/endpoint/pci-epf-core.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Kishon, please review this patch, thanks. Lorenzo > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > index e9289d10f822..538e902b0ba6 100644 > --- a/drivers/pci/endpoint/pci-epf-core.c > +++ b/drivers/pci/endpoint/pci-epf-core.c > @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) > return; > > mutex_lock(&pci_epf_mutex); > - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) > + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { > + list_del(&group->group_entry); > pci_ep_cfs_remove_epf_group(group); > + } > list_del(&driver->epf_group); > mutex_unlock(&pci_epf_mutex); > } > -- > 2.17.1 >
Hi Shunsuke, On 21/06/21 12:30 pm, Shunsuke Mie wrote: > All of entries are freed in a loop, however, the freed entry is accessed > by list_del() after the loop. > > When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() > is called, and occurred the use after free. Therefore, kernel panics > randomly after or while the module unloading. > > I tested this patch with r8a77951-Salvator-xs boards. Can you provide the crash dump? > > Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") > Signed-off-by: Shunsuke Mie <mie@igel.co.jp> > --- > drivers/pci/endpoint/pci-epf-core.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > index e9289d10f822..538e902b0ba6 100644 > --- a/drivers/pci/endpoint/pci-epf-core.c > +++ b/drivers/pci/endpoint/pci-epf-core.c > @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) > return; > > mutex_lock(&pci_epf_mutex); > - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) > + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { > + list_del(&group->group_entry); Need full crash dump to see if this is really required or not. Ideally this should be handled by configfs (or a configfs API could be used). Thanks, Kishon
Hi Kishon, 2021年12月7日(火) 16:26 Kishon Vijay Abraham I <kishon@ti.com>: > > Hi Shunsuke, > > On 21/06/21 12:30 pm, Shunsuke Mie wrote: > > All of entries are freed in a loop, however, the freed entry is accessed > > by list_del() after the loop. > > > > When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() > > is called, and occurred the use after free. Therefore, kernel panics > > randomly after or while the module unloading. > > > > I tested this patch with r8a77951-Salvator-xs boards. > > Can you provide the crash dump? Ok. However, that is use-after-free bug. so, the crash log is changed randomly. I'll send some crash dumps. > > > > Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") > > Signed-off-by: Shunsuke Mie <mie@igel.co.jp> > > --- > > drivers/pci/endpoint/pci-epf-core.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > > index e9289d10f822..538e902b0ba6 100644 > > --- a/drivers/pci/endpoint/pci-epf-core.c > > +++ b/drivers/pci/endpoint/pci-epf-core.c > > @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) > > return; > > > > mutex_lock(&pci_epf_mutex); > > - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) > > + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { > > + list_del(&group->group_entry); > > Need full crash dump to see if this is really required or not. Ideally this > should be handled by configfs (or a configfs API could be used). > > Thanks, > Kishon
Hi Kishon, This is the crash log. I think you can reproduce this problem by loading and unloading the pci-epf-test modules some times, but I don't think you'll see similar logs in your environment. The pci_ep_cfs_remove_epf_group function calls kfree for the `group`, however a member of group, `group_entry``, is accessed by a list_del() after the loop. The patch changes to remove list entries to prevent the accessing after freed object. Thanks, Shunsuke 2021年12月7日(火) 16:44 Shunsuke Mie <mie@igel.co.jp>: > > Hi Kishon, > > 2021年12月7日(火) 16:26 Kishon Vijay Abraham I <kishon@ti.com>: > > > > Hi Shunsuke, > > > > On 21/06/21 12:30 pm, Shunsuke Mie wrote: > > > All of entries are freed in a loop, however, the freed entry is accessed > > > by list_del() after the loop. > > > > > > When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() > > > is called, and occurred the use after free. Therefore, kernel panics > > > randomly after or while the module unloading. > > > > > > I tested this patch with r8a77951-Salvator-xs boards. > > > > Can you provide the crash dump? > Ok. However, that is use-after-free bug. so, the crash log is changed randomly. > I'll send some crash dumps. > > > > > > Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") > > > Signed-off-by: Shunsuke Mie <mie@igel.co.jp> > > > --- > > > drivers/pci/endpoint/pci-epf-core.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > > > index e9289d10f822..538e902b0ba6 100644 > > > --- a/drivers/pci/endpoint/pci-epf-core.c > > > +++ b/drivers/pci/endpoint/pci-epf-core.c > > > @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) > > > return; > > > > > > mutex_lock(&pci_epf_mutex); > > > - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) > > > + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { > > > + list_del(&group->group_entry); > > > > Need full crash dump to see if this is really required or not. Ideally this > > should be handled by configfs (or a configfs API could be used). > > > > Thanks, > > Kishon
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index e9289d10f822..538e902b0ba6 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -202,8 +202,10 @@ static void pci_epf_remove_cfs(struct pci_epf_driver *driver) return; mutex_lock(&pci_epf_mutex); - list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) + list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry) { + list_del(&group->group_entry); pci_ep_cfs_remove_epf_group(group); + } list_del(&driver->epf_group); mutex_unlock(&pci_epf_mutex); }
All of entries are freed in a loop, however, the freed entry is accessed by list_del() after the loop. When epf driver that includes pci-epf-test unload, the pci_epf_remove_cfs() is called, and occurred the use after free. Therefore, kernel panics randomly after or while the module unloading. I tested this patch with r8a77951-Salvator-xs boards. Fixes: ef1433f ("PCI: endpoint: Create configfs entry for each pci_epf_device_id table entry") Signed-off-by: Shunsuke Mie <mie@igel.co.jp> --- drivers/pci/endpoint/pci-epf-core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)