[Linux-kernel-mentees] [PATCH] net: qrtr: Reintroduce ARCH_QCOM as a dependency for QRTR

Anant Thazhemadam anant.thazhemadam at gmail.com
Tue Sep 8 23:33:28 UTC 2020

Removing ARCH_QCOM, as a dependency for QRTR begins to give rise to
issues with respect to maintaining reference count integrity and
suspicious rcu usage.

The bugs resolved by making QRTR dependent on ARCH_QCOM include:

* WARNING: refcount bug in qrtr_node_lookup
Reported-by: syzbot+c613e88b3093ebf3686e at syzkaller.appspotmail.com
* WARNING: refcount bug in qrtr_recvmsg
Reported-by: syzbot+d0f27d9af17914bf253b at syzkaller.appspotmail.com
* WARNING: suspicious RCU usage in ctrl_cmd_new_lookup
Reported-by: syzbot+3025b9294f8cb0ede850 at syzkaller.appspotmail.com
* WARNING: suspicious RCU usage in qrtr_ns_worker
Reported-by: syzbot+0f84f6eed90503da72fc at syzkaller.appspotmail.com

Signed-off-by: Anant Thazhemadam <anant.thazhemadam at gmail.com>
As I understand it, QRTR was initially dependent upon ARCH_QCOM, but was 
removed since not all modems using IPC Router protocol required the 
support provided for Qualcomm platforms. 
However, wouldn't ARCH_QCOM be required by the modems that require the 
support provided for Qualcomm platforms?
The configuration ARCH_QCOM isn't exactly the easiest to find, especially, 
for those who don't know what they're looking for (syzbot included, I 
I don't feel like the tradeoff of not depending on ARCH_QCOM over giving 
rise to potential bugs is worth it. 
Is NOT having QRTR depend on ARCH_QCOM so critical that it supersedes the 
priority of not giving rise to potential bugs?

 net/qrtr/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/qrtr/Kconfig b/net/qrtr/Kconfig
index b4020b84760f..8156d0f3656b 100644
--- a/net/qrtr/Kconfig
+++ b/net/qrtr/Kconfig
@@ -4,6 +4,7 @@
 config QRTR
 	tristate "Qualcomm IPC Router support"
+	depends on ARCH_QCOM
 	  Say Y if you intend to use Qualcomm IPC router protocol.  The
 	  protocol is used to communicate with services provided by other

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