linux-kernel - Re: [PATCH] vfio/pci: fix memory leaks in alloc_perm

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Message-ID: <20200511083547.24718bcc.cohuck@redhat.com>
Date:   Mon, 11 May 2020 08:35:47 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Qian Cai <cai@....pw>
Cc:     alex.williamson@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfio/pci: fix memory leaks in alloc_perm_bits()

On Sun, 10 May 2020 12:16:56 -0400
Qian Cai <cai@....pw> wrote:

> vfio_pci_disable() calls vfio_config_free() but forgets to call
> free_perm_bits() resulting in memory leaks,
> 
> unreferenced object 0xc000000c4db2dee0 (size 16):
>   comm "qemu-kvm", pid 4305, jiffies 4295020272 (age 3463.780s)
>   hex dump (first 16 bytes):
>     00 00 ff 00 ff ff ff ff ff ff ff ff ff ff 00 00  ................
>   backtrace:
>     [<00000000a6a4552d>] alloc_perm_bits+0x58/0xe0 [vfio_pci]
>     [<00000000ac990549>] vfio_config_init+0xdf0/0x11b0 [vfio_pci]
>     init_pci_cap_msi_perm at drivers/vfio/pci/vfio_pci_config.c:1125
>     (inlined by) vfio_msi_cap_len at drivers/vfio/pci/vfio_pci_config.c:1180
>     (inlined by) vfio_cap_len at drivers/vfio/pci/vfio_pci_config.c:1241
>     (inlined by) vfio_cap_init at drivers/vfio/pci/vfio_pci_config.c:1468
>     (inlined by) vfio_config_init at drivers/vfio/pci/vfio_pci_config.c:1707
>     [<000000006db873a1>] vfio_pci_open+0x234/0x700 [vfio_pci]
>     [<00000000630e1906>] vfio_group_fops_unl_ioctl+0x8e0/0xb84 [vfio]
>     [<000000009e34c54f>] ksys_ioctl+0xd8/0x130
>     [<000000006577923d>] sys_ioctl+0x28/0x40
>     [<000000006d7b1cf2>] system_call_exception+0x114/0x1e0
>     [<0000000008ea7dd5>] system_call_common+0xf0/0x278
> unreferenced object 0xc000000c4db2e330 (size 16):
>   comm "qemu-kvm", pid 4305, jiffies 4295020272 (age 3463.780s)
>   hex dump (first 16 bytes):
>     00 ff ff 00 ff ff ff ff ff ff ff ff ff ff 00 00  ................
>   backtrace:
>     [<000000004c71914f>] alloc_perm_bits+0x44/0xe0 [vfio_pci]
>     [<00000000ac990549>] vfio_config_init+0xdf0/0x11b0 [vfio_pci]
>     [<000000006db873a1>] vfio_pci_open+0x234/0x700 [vfio_pci]
>     [<00000000630e1906>] vfio_group_fops_unl_ioctl+0x8e0/0xb84 [vfio]
>     [<000000009e34c54f>] ksys_ioctl+0xd8/0x130
>     [<000000006577923d>] sys_ioctl+0x28/0x40
>     [<000000006d7b1cf2>] system_call_exception+0x114/0x1e0
>     [<0000000008ea7dd5>] system_call_common+0xf0/0x278
> 
> Fixes: 89e1f7d4c66d ("vfio: Add PCI device driver")
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>  drivers/vfio/pci/vfio_pci_config.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
> index 90c0b80f8acf..f9fdc72a5f4e 100644
> --- a/drivers/vfio/pci/vfio_pci_config.c
> +++ b/drivers/vfio/pci/vfio_pci_config.c
> @@ -1728,6 +1728,7 @@ void vfio_config_free(struct vfio_pci_device *vdev)
>  	vdev->vconfig = NULL;
>  	kfree(vdev->pci_config_map);
>  	vdev->pci_config_map = NULL;
> +	free_perm_bits(vdev->msi_perm);
>  	kfree(vdev->msi_perm);
>  	vdev->msi_perm = NULL;
>  }

Seems to be the only perm bits that were missed.

Reviewed-by: Cornelia Huck <cohuck@...hat.com>