netdev - [PATCH net-next] net: ethtool: phy: Distinguish whether dev is got by phy start or doit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240913080714.1809254-1-lizhi.xu@windriver.com>
Date: Fri, 13 Sep 2024 16:07:13 +0800
From: Lizhi Xu <lizhi.xu@...driver.com>
To: <syzbot+e9ed4e4368d450c8f9db@...kaller.appspotmail.com>
CC: <christophe.leroy@...roup.eu>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>,
        <linux-kernel@...r.kernel.org>, <maxime.chevallier@...tlin.com>,
        <netdev@...r.kernel.org>, <pabeni@...hat.com>,
        <syzkaller-bugs@...glegroups.com>
Subject: [PATCH net-next] net: ethtool: phy: Distinguish whether dev is got by phy start or doit

Syzbot reported a refcount bug in ethnl_phy_done.
This is because when executing ethnl_phy_done, it does not know who obtained
the dev(it can be got by ethnl_phy_doit or ethnl_phy_start) and directly
executes ethnl_parse_header_dev_put as long as the dev is not NULL.
Add dev_start_doit to the structure phy_req_info to distinguish who obtains dev.

Fixes: 17194be4c8e1 ("net: ethtool: Introduce a command to list PHYs on an interface")
Reported-and-tested-by: syzbot+e9ed4e4368d450c8f9db@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e9ed4e4368d450c8f9db
Signed-off-by: Lizhi Xu <lizhi.xu@...driver.com>
---
 net/ethtool/phy.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/phy.c b/net/ethtool/phy.c
index 4ef7c6e32d10..321a7f89803f 100644
--- a/net/ethtool/phy.c
+++ b/net/ethtool/phy.c
@@ -13,6 +13,7 @@
 struct phy_req_info {
 	struct ethnl_req_info		base;
 	struct phy_device_node		*pdn;
+	u8 dev_start_doit;
 };
 
 #define PHY_REQINFO(__req_base) \
@@ -157,6 +158,9 @@ int ethnl_phy_doit(struct sk_buff *skb, struct genl_info *info)
 	if (ret < 0)
 		return ret;
 
+	if (req_info.base.dev)
+		req_info.dev_start_doit = 0;
+
 	rtnl_lock();
 
 	ret = ethnl_phy_parse_request(&req_info.base, tb, info->extack);
@@ -223,10 +227,14 @@ int ethnl_phy_start(struct netlink_callback *cb)
 					 false);
 	ctx->ifindex = 0;
 	ctx->phy_index = 0;
+	ctx->phy_req_info->dev_start_doit = 0;
 
 	if (ret)
 		kfree(ctx->phy_req_info);
 
+	if (ctx->phy_req_info->base.dev)
+		ctx->phy_req_info->dev_start_doit = 1;
+
 	return ret;
 }
 
@@ -234,7 +242,7 @@ int ethnl_phy_done(struct netlink_callback *cb)
 {
 	struct ethnl_phy_dump_ctx *ctx = (void *)cb->ctx;
 
-	if (ctx->phy_req_info->base.dev)
+	if (ctx->phy_req_info->base.dev && ctx->phy_req_info->dev_start_doit)
 		ethnl_parse_header_dev_put(&ctx->phy_req_info->base);
 
 	kfree(ctx->phy_req_info);
-- 
2.43.0