[PATCH net-next] ethtool: fix null-ptr-deref on ref tracker

dev can be a NULL here, not all requests set require_dev.

Fixes: e4b8954074f6 ("netlink: add net device refcount tracker to struct ethnl_req_info")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/ethtool/netlink.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 23f32a995099..767fb3f17267 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c

@@ -141,8 +141,10 @@ int ethnl_parse_header_dev_get(struct ethnl_req_info *req_info,
 		return -EINVAL;
 	}
 
-	req_info->dev = dev;
-	netdev_tracker_alloc(dev, &req_info->dev_tracker, GFP_KERNEL);
+	if (dev) {
+		req_info->dev = dev;
+		netdev_tracker_alloc(dev, &req_info->dev_tracker, GFP_KERNEL);
+	}
 	req_info->flags = flags;
 	return 0;
 }

-- 
2.31.1

On 12/13/21 5:39 PM, Jakub Kicinski wrote:

Oh I am reading your patch after I sent mine.


Please use edumazet@google.com next time, because eric.dumazet@gmail.com has

huge lag (typical vger -> accounts@gmail.com issues)


Reviewed-by: Eric Dumazet <redacted>


Thanks !

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller [off-list ref]:

On Mon, 13 Dec 2021 17:39:02 -0800 you wrote:

dev can be a NULL here, not all requests set require_dev.

Fixes: e4b8954074f6 ("netlink: add net device refcount tracker to struct ethnl_req_info")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/ethtool/netlink.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Here is the summary with links:
  - [net-next] ethtool: fix null-ptr-deref on ref tracker
    https://git.kernel.org/netdev/net-next/c/0976b888a150

You are awesome, thank you!
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