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Input: synaptics-rmi4 - fix use after free (more completely)

Message ID e77756aa-c0f1-44a8-bcd6-a46fe954b195@moroto.mountain
State New
Headers show
Series Input: synaptics-rmi4 - fix use after free (more completely) | expand

Commit Message

Dan Carpenter Feb. 22, 2024, 8:53 a.m. UTC 
From: Brad Spengler <spender@grsecurity.net>

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 <torsten.hilbrich@secunet.com>
Closes: https://lore.kernel.org/all/1932038e-2776-04ac-5fcd-b15bb3cd088d@secunet.com/
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/input/rmi4/rmi_bus.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

Mathias Krause Feb. 22, 2024, 2:19 p.m. UTC | #1 
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 <torsten.hilbrich@secunet.com>
>> Closes: https://lore.kernel.org/all/1932038e-2776-04ac-5fcd-b15bb3cd088d@secunet.com/
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215604
>> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
>> ---
>>  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 <minipli@grsecurity.net>

So, forget about that one, sorry.
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Patch

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);
 }