[tip:irq/core] genirq: Prevent use-after-free and work list corruption

[tip-bot for Prasad Sodagudi]

Commit-ID:  59c39840f5abf4a71e1810a8da71aaccd6c17d26
Gitweb:     https://git.kernel.org/tip/59c39840f5abf4a71e1810a8da71aaccd6c17d26
Author:     Prasad Sodagudi <psodagud@xxxxxxxxxxxxxx>
AuthorDate: Sun, 24 Mar 2019 07:57:04 -0700
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 24 Mar 2019 22:13:17 +0100

genirq: Prevent use-after-free and work list corruption

When irq_set_affinity_notifier() replaces the notifier, then the
reference count on the old notifier is dropped which causes it to be
freed. But nothing ensures that the old notifier is not longer queued
in the work list. If it is queued this results in a use after free and
possibly in work list corruption.

Ensure that the work is canceled before the reference is dropped.

Signed-off-by: Prasad Sodagudi <psodagud@xxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: marc.zyngier@xxxxxxx
Link: https://lkml.kernel.org/r/1553439424-6529-1-git-send-email-psodagud@xxxxxxxxxxxxxx

---
 kernel/irq/manage.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 1401afa0d58a..53a081392115 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -357,8 +357,10 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 	desc->affinity_notify = notify;
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 
-	if (old_notify)
+	if (old_notify) {
+		cancel_work_sync(&old_notify->work);
 		kref_put(&old_notify->kref, old_notify->release);
+	}
 
 	return 0;
 }