Subject: Re: [PATCH net] virtio_net: fix device mismatch in devm_kzalloc/devm_kfree

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 2 Jan 2026 06:27:56 -0500

On Fri, Jan 02, 2026 at 03:49:00PM +0530, Kommula Shiva Shankar wrote:
> Initial rss_hdr allocation uses virtio_device->device,
> but virtnet_set_queues() frees using net_device->device.
> This device mismatch causing below devres warning
> 
> [ 3788.514041] ------------[ cut here ]------------
> [ 3788.514044] WARNING: drivers/base/devres.c:1095 at devm_kfree+0x84/0x98, CPU#16: vdpa/1463
> [ 3788.514054] Modules linked in: octep_vdpa virtio_net virtio_vdpa [last unloaded: virtio_vdpa]
> [ 3788.514064] CPU: 16 UID: 0 PID: 1463 Comm: vdpa Tainted: G        W           6.18.0 #10 PREEMPT
> [ 3788.514067] Tainted: [W]=WARN
> [ 3788.514069] Hardware name: Marvell CN106XX board (DT)
> [ 3788.514071] pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> [ 3788.514074] pc : devm_kfree+0x84/0x98
> [ 3788.514076] lr : devm_kfree+0x54/0x98
> [ 3788.514079] sp : ffff800084e2f220
> [ 3788.514080] x29: ffff800084e2f220 x28: ffff0003b2366000 x27: 000000000000003f
> [ 3788.514085] x26: 000000000000003f x25: ffff000106f17c10 x24: 0000000000000080
> [ 3788.514089] x23: ffff00045bb8ab08 x22: ffff00045bb8a000 x21: 0000000000000018
> [ 3788.514093] x20: ffff0004355c3080 x19: ffff00045bb8aa00 x18: 0000000000080000
> [ 3788.514098] x17: 0000000000000040 x16: 000000000000001f x15: 000000000007ffff
> [ 3788.514102] x14: 0000000000000488 x13: 0000000000000005 x12: 00000000000fffff
> [ 3788.514106] x11: ffffffffffffffff x10: 0000000000000005 x9 : ffff800080c8c05c
> [ 3788.514110] x8 : ffff800084e2eeb8 x7 : 0000000000000000 x6 : 000000000000003f
> [ 3788.514115] x5 : ffff8000831bafe0 x4 : ffff800080c8b010 x3 : ffff0004355c3080
> [ 3788.514119] x2 : ffff0004355c3080 x1 : 0000000000000000 x0 : 0000000000000000
> [ 3788.514123] Call trace:
> [ 3788.514125]  devm_kfree+0x84/0x98 (P)
> [ 3788.514129]  virtnet_set_queues+0x134/0x2e8 [virtio_net]
> [ 3788.514135]  virtnet_probe+0x9c0/0xe00 [virtio_net]
> [ 3788.514139]  virtio_dev_probe+0x1e0/0x338
> [ 3788.514144]  really_probe+0xc8/0x3a0
> [ 3788.514149]  __driver_probe_device+0x84/0x170
> [ 3788.514152]  driver_probe_device+0x44/0x120
> [ 3788.514155]  __device_attach_driver+0xc4/0x168
> [ 3788.514158]  bus_for_each_drv+0x8c/0xf0
> [ 3788.514161]  __device_attach+0xa4/0x1c0
> [ 3788.514164]  device_initial_probe+0x1c/0x30
> [ 3788.514168]  bus_probe_device+0xb4/0xc0
> [ 3788.514170]  device_add+0x614/0x828
> [ 3788.514173]  register_virtio_device+0x214/0x258
> [ 3788.514175]  virtio_vdpa_probe+0xa0/0x110 [virtio_vdpa]
> [ 3788.514179]  vdpa_dev_probe+0xa8/0xd8
> [ 3788.514183]  really_probe+0xc8/0x3a0
> [ 3788.514186]  __driver_probe_device+0x84/0x170
> [ 3788.514189]  driver_probe_device+0x44/0x120
> [ 3788.514192]  __device_attach_driver+0xc4/0x168
> [ 3788.514195]  bus_for_each_drv+0x8c/0xf0
> [ 3788.514197]  __device_attach+0xa4/0x1c0
> [ 3788.514200]  device_initial_probe+0x1c/0x30
> [ 3788.514203]  bus_probe_device+0xb4/0xc0
> [ 3788.514206]  device_add+0x614/0x828
> [ 3788.514209]  _vdpa_register_device+0x58/0x88
> [ 3788.514211]  octep_vdpa_dev_add+0x104/0x228 [octep_vdpa]
> [ 3788.514215]  vdpa_nl_cmd_dev_add_set_doit+0x2d0/0x3c0
> [ 3788.514218]  genl_family_rcv_msg_doit+0xe4/0x158
> [ 3788.514222]  genl_rcv_msg+0x218/0x298
> [ 3788.514225]  netlink_rcv_skb+0x64/0x138
> [ 3788.514229]  genl_rcv+0x40/0x60
> [ 3788.514233]  netlink_unicast+0x32c/0x3b0
> [ 3788.514237]  netlink_sendmsg+0x170/0x3b8
> [ 3788.514241]  __sys_sendto+0x12c/0x1c0
> [ 3788.514246]  __arm64_sys_sendto+0x30/0x48
> [ 3788.514249]  invoke_syscall.constprop.0+0x58/0xf8
> [ 3788.514255]  do_el0_svc+0x48/0xd0
> [ 3788.514259]  el0_svc+0x48/0x210
> [ 3788.514264]  el0t_64_sync_handler+0xa0/0xe8
> [ 3788.514268]  el0t_64_sync+0x198/0x1a0
> [ 3788.514271] ---[ end trace 0000000000000000 ]---
> 
> Fix by using virtio_device->device consistently for
> allocation and deallocation
> 
> Fixes: 4944be2f5ad8c ("virtio_net: Allocate rss_hdr with devres")
> Signed-off-by: Kommula Shiva Shankar <[email-masked]>

And not just a warning, it can be a memleak/double free, right?

Acked-by: Michael S. Tsirkin <[email-masked]>

> ---
>  drivers/net/virtio_net.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 1bb3aeca66c6..22d894101c01 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3791,7 +3791,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
>  	if (vi->has_rss && !netif_is_rxfh_configured(dev)) {
>  		old_rss_hdr = vi->rss_hdr;
>  		old_rss_trailer = vi->rss_trailer;
> -		vi->rss_hdr = devm_kzalloc(&dev->dev, virtnet_rss_hdr_size(vi), GFP_KERNEL);
> +		vi->rss_hdr = devm_kzalloc(&vi->vdev->dev, virtnet_rss_hdr_size(vi), GFP_KERNEL);
>  		if (!vi->rss_hdr) {
>  			vi->rss_hdr = old_rss_hdr;
>  			return -ENOMEM;
> @@ -3802,7 +3802,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
>  
>  		if (!virtnet_commit_rss_command(vi)) {
>  			/* restore ctrl_rss if commit_rss_command failed */
> -			devm_kfree(&dev->dev, vi->rss_hdr);
> +			devm_kfree(&vi->vdev->dev, vi->rss_hdr);
>  			vi->rss_hdr = old_rss_hdr;
>  			vi->rss_trailer = old_rss_trailer;
>  
> @@ -3810,7 +3810,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
>  				 queue_pairs);
>  			return -EINVAL;
>  		}
> -		devm_kfree(&dev->dev, old_rss_hdr);
> +		devm_kfree(&vi->vdev->dev, old_rss_hdr);
>  		goto succ;
>  	}
>  
> -- 
> 2.48.1