From: Xiaoming Ni <nixiaoming@huawei.com> mainline inclusion from mainline-v5.5-rc1 commit 1a50cb80f219c44adb6265f5071b81fc3c1deced category: bugfix bugzilla: NA CVE: NA --------------------------------------------- [ Upstream commit 1a50cb80f219c44adb6265f5071b81fc3c1deced ] Registering the same notifier to a hook repeatedly can cause the hook list to form a ring or lose other members of the list. case1: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); case2: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_call_chain(&test_notifier_list, 0, NULL); case3: lose other hook test2 atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); atomic_notifier_chain_register(&test_notifier_list, &test1); case4: Unregister returns 0, but the hook is still in the linked list, and it is not really registered. If you call notifier_call_chain after ko is unloaded, it will trigger oops. If the system is configured with softlockup_panic and the same hook is repeatedly registered on the panic_notifier_list, it will cause a loop panic. Add a check in notifier_chain_register(), intercepting duplicate registrations to avoid infinite loops Link: http://lkml.kernel.org/r/1568861888-34045-2-git-send-email-nixiaoming@huawei... Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Reviewed-by: Vasily Averin <vvs@virtuozzo.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: J. Bruce Fields <bfields@fieldses.org> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: David S. Miller <davem@davemloft.net> Cc: Jeff Layton <jlayton@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Nadia Derbey <Nadia.Derbey@bull.net> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Sam Protsenko <semen.protsenko@linaro.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Xiaoming Ni <nixiaoming@huawei.com> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com> Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- kernel/notifier.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/notifier.c b/kernel/notifier.c index 6196af8a8223..c6de38836f50 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -22,6 +22,11 @@ static int notifier_chain_register(struct notifier_block **nl, struct notifier_block *n) { while ((*nl) != NULL) { + if (unlikely((*nl) == n)) { + WARN(1, "double register detected"); + return 0; + } + if (n->priority > (*nl)->priority) break; nl = &((*nl)->next); -- 2.25.1