From: Brad Spengler <[email protected]>
Grsecurity uses memory poisoning and detected a use after free in
rmi_unregister_function(). A fix for this was merged into the
grsecurity patchset. I detected the user after free later using static
analysis and sent a partial fix as commit eb988e46da2e ("Input:
synaptics-rmi4 - fix use after free in rmi_unregister_function()").
However, my patch meant that the grsecurity patchset didn't apply cleanly
and forced everyone to re-visit this issue.
The bug is that we must not call device_del() until after calling
irq_dispose_mapping().
Fixes: 24d28e4f1271 ("Input: synaptics-rmi4 - convert irq distribution to irq_domain")
Reported-by: Torsten Hilbrich <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
Signed-off-by: Dan Carpenter <[email protected]>
---
drivers/input/rmi4/rmi_bus.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
index 1b45b1d3077d..02acc81b9d3e 100644
--- a/drivers/input/rmi4/rmi_bus.c
+++ b/drivers/input/rmi4/rmi_bus.c
@@ -275,12 +275,11 @@ void rmi_unregister_function(struct rmi_function *fn)
rmi_dbg(RMI_DEBUG_CORE, &fn->dev, "Unregistering F%02X.\n",
fn->fd.function_number);
- device_del(&fn->dev);
- of_node_put(fn->dev.of_node);
-
for (i = 0; i < fn->num_of_irqs; i++)
irq_dispose_mapping(fn->irq[i]);
+ device_del(&fn->dev);
+ of_node_put(fn->dev.of_node);
put_device(&fn->dev);
}
--
2.43.0
Hi Dan, Torsten,
On 22.02.24 09:53, Dan Carpenter wrote:
> From: Brad Spengler <[email protected]>
>
> Grsecurity uses memory poisoning and detected a use after free in
> rmi_unregister_function(). A fix for this was merged into the
> grsecurity patchset. I detected the user after free later using static
^^^^ use after free
> analysis and sent a partial fix as commit eb988e46da2e ("Input:
> synaptics-rmi4 - fix use after free in rmi_unregister_function()").
> However, my patch meant that the grsecurity patchset didn't apply cleanly
> and forced everyone to re-visit this issue.
Indeed. We even noticed that your patch was incomplete back then but
urgent matters kept us from following-up. Then came holidays and this
simply went forgotten :(
>
> The bug is that we must not call device_del() until after calling
> irq_dispose_mapping().
Unfortunately, this is only half the truth. We investigated this further
and there's another bug that got introduced in commit 24d28e4f1271
("Input: synaptics-rmi4 - convert irq distribution to irq_domain"). The
IRQ domain has a UAF issue as well. I'll send the patch soon -- wanted
to do so this week, but, again, more urgent matters interrupted this.
>
> Fixes: 24d28e4f1271 ("Input: synaptics-rmi4 - convert irq distribution to irq_domain")
> Reported-by: Torsten Hilbrich <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> drivers/input/rmi4/rmi_bus.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
> index 1b45b1d3077d..02acc81b9d3e 100644
> --- a/drivers/input/rmi4/rmi_bus.c
> +++ b/drivers/input/rmi4/rmi_bus.c
> @@ -275,12 +275,11 @@ void rmi_unregister_function(struct rmi_function *fn)
> rmi_dbg(RMI_DEBUG_CORE, &fn->dev, "Unregistering F%02X.\n",
> fn->fd.function_number);
>
> - device_del(&fn->dev);
> - of_node_put(fn->dev.of_node);
> -
> for (i = 0; i < fn->num_of_irqs; i++)
> irq_dispose_mapping(fn->irq[i]);
>
> + device_del(&fn->dev);
> + of_node_put(fn->dev.of_node);
> put_device(&fn->dev);
> }
>
Acked-by: Mathias Krause <[email protected]>
On 22.02.24 15:08, Mathias Krause wrote:
>>
>> The bug is that we must not call device_del() until after calling
>> irq_dispose_mapping().
>
> Unfortunately, this is only half the truth. We investigated this further
> and there's another bug that got introduced in commit 24d28e4f1271
> ("Input: synaptics-rmi4 - convert irq distribution to irq_domain"). The
> IRQ domain has a UAF issue as well. I'll send the patch soon -- wanted
> to do so this week, but, again, more urgent matters interrupted this.
Unfortunately, I send that Email too fast. Looking at the backtrace
again, it's just the other bug that needs fixing (a UAF in
rmi_driver_remove()). Will sent a patch really soon now!
>
>>
>> Fixes: 24d28e4f1271 ("Input: synaptics-rmi4 - convert irq distribution to irq_domain")
>> Reported-by: Torsten Hilbrich <[email protected]>
>> Closes: https://lore.kernel.org/all/[email protected]/
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
>> Signed-off-by: Dan Carpenter <[email protected]>
>> ---
>> drivers/input/rmi4/rmi_bus.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
>> index 1b45b1d3077d..02acc81b9d3e 100644
>> --- a/drivers/input/rmi4/rmi_bus.c
>> +++ b/drivers/input/rmi4/rmi_bus.c
>> @@ -275,12 +275,11 @@ void rmi_unregister_function(struct rmi_function *fn)
>> rmi_dbg(RMI_DEBUG_CORE, &fn->dev, "Unregistering F%02X.\n",
>> fn->fd.function_number);
>>
>> - device_del(&fn->dev);
>> - of_node_put(fn->dev.of_node);
>> -
>> for (i = 0; i < fn->num_of_irqs; i++)
>> irq_dispose_mapping(fn->irq[i]);
>>
>> + device_del(&fn->dev);
>> + of_node_put(fn->dev.of_node);
>> put_device(&fn->dev);
>> }
>>
>
> Acked-by: Mathias Krause <[email protected]>
So, forget about that one, sorry.
On Thu, Feb 22, 2024 at 03:19:49PM +0100, Mathias Krause wrote:
> On 22.02.24 15:08, Mathias Krause wrote:
> >>
> >> The bug is that we must not call device_del() until after calling
> >> irq_dispose_mapping().
> >
> > Unfortunately, this is only half the truth. We investigated this further
> > and there's another bug that got introduced in commit 24d28e4f1271
> > ("Input: synaptics-rmi4 - convert irq distribution to irq_domain"). The
> > IRQ domain has a UAF issue as well. I'll send the patch soon -- wanted
> > to do so this week, but, again, more urgent matters interrupted this.
>
> Unfortunately, I send that Email too fast. Looking at the backtrace
> again, it's just the other bug that needs fixing (a UAF in
> rmi_driver_remove()). Will sent a patch really soon now!
>
> >
> >>
> >> Fixes: 24d28e4f1271 ("Input: synaptics-rmi4 - convert irq distribution to irq_domain")
> >> Reported-by: Torsten Hilbrich <[email protected]>
> >> Closes: https://lore.kernel.org/all/[email protected]/
> >> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
> >> Signed-off-by: Dan Carpenter <[email protected]>
> >> ---
> >> drivers/input/rmi4/rmi_bus.c | 5 ++---
> >> 1 file changed, 2 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
> >> index 1b45b1d3077d..02acc81b9d3e 100644
> >> --- a/drivers/input/rmi4/rmi_bus.c
> >> +++ b/drivers/input/rmi4/rmi_bus.c
> >> @@ -275,12 +275,11 @@ void rmi_unregister_function(struct rmi_function *fn)
> >> rmi_dbg(RMI_DEBUG_CORE, &fn->dev, "Unregistering F%02X.\n",
> >> fn->fd.function_number);
> >>
> >> - device_del(&fn->dev);
> >> - of_node_put(fn->dev.of_node);
> >> -
> >> for (i = 0; i < fn->num_of_irqs; i++)
> >> irq_dispose_mapping(fn->irq[i]);
> >>
> >> + device_del(&fn->dev);
> >> + of_node_put(fn->dev.of_node);
> >> put_device(&fn->dev);
> >> }
> >>
> >
> > Acked-by: Mathias Krause <[email protected]>
>
> So, forget about that one, sorry.
Right, I do not think this patch is needed. The "fn" will stay in memory
until the last reference to fn->dev is dropped. So the original patch
was enough for this particular issue, and Mathias' patch fixes slightly
different UAF.
Thanks.
--
Dmitry