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Wed, 05 Mar 2025 15:53:46 -0800 (PST) From: Qasim Ijaz To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, atenart@kernel.org, jdamato@fastly.com, aleksander.lobakin@intel.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] net-sysfs: fix NULL pointer dereference Date: Wed, 5 Mar 2025 23:53:07 +0000 Message-Id: <20250305235307.14829-1-qasdev00@gmail.com> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Commit <79c61899b5ee> introduces a potential NULL pointer dereference in the sysfs_rtnl_lock() function when initialising kn: kn = sysfs_break_active_protection(kobj, attr); The commit overlooks the fact that sysfs_break_active_protection can return NULL if kernfs_find_and_get() fails to find and get the kernfs_node with the given name. Later on the code calls sysfs_unbreak_active_protection(kn) unconditionally, which could lead to a NULL pointer dereference. Resolve this bug by introducing a NULL check before using kn in the sysfs_unbreak_active_protection() call. Signed-off-by: Qasim Ijaz Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes") --- net/core/net-sysfs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 8d9dc048a548..c5085588e536 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -117,7 +117,8 @@ static int sysfs_rtnl_lock(struct kobject *kobj, struct attribute *attr, * the rtnl lock. */ unbreak: - sysfs_unbreak_active_protection(kn); + if (kn) + sysfs_unbreak_active_protection(kn); dev_put(ndev); return ret;