linux-kernel - [PATCH] KVM: fix memory leak in kvm_io_bus_unregister

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Date:   Sat, 29 Aug 2020 21:34:05 -0700
From:   Rustam Kovhaev <rkovhaev@...il.com>
To:     pbonzini@...hat.com, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        Rustam Kovhaev <rkovhaev@...il.com>
Subject: [PATCH] KVM: fix memory leak in kvm_io_bus_unregister_dev()

when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing
the bus, we should iterate over all other devices linked to it and call
kvm_iodevice_destructor() for them

Reported-and-tested-by: syzbot+f196caa45793d6374707@...kaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707
Signed-off-by: Rustam Kovhaev <rkovhaev@...il.com>
---
 virt/kvm/kvm_main.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 67cd0b88a6b6..646aa7b82548 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4332,7 +4332,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 			       struct kvm_io_device *dev)
 {
-	int i;
+	int i, j;
 	struct kvm_io_bus *new_bus, *bus;
 
 	bus = kvm_get_bus(kvm, bus_idx);
@@ -4351,6 +4351,11 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 			  GFP_KERNEL_ACCOUNT);
 	if (!new_bus)  {
 		pr_err("kvm: failed to shrink bus, removing it completely\n");
+		for (j = 0; j < bus->dev_count; j++) {
+			if (j == i)
+				continue;
+			kvm_iodevice_destructor(bus->range[j].dev);
+		}
 		goto broken;
 	}
 
-- 
2.28.0