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authorXiaoming Ni <nixiaoming@huawei.com>2019-12-04 16:50:39 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-04 19:44:12 -0800
commit1a50cb80f219c44adb6265f5071b81fc3c1deced (patch)
tree7ea13de39f956015bdc6d7644dc34dcccc221c11 /kernel
parentd717e7da45b382c09cee4f1e03ce30124e672e07 (diff)
kernel/notifier.c: intercept duplicate registrations to avoid infinite loops
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.com 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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/notifier.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/notifier.c b/kernel/notifier.c
index d9f5081d578d..30bedb8be6dd 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -23,7 +23,10 @@ static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n)
{
while ((*nl) != NULL) {
- WARN_ONCE(((*nl) == n), "double register detected");
+ if (unlikely((*nl) == n)) {
+ WARN(1, "double register detected");
+ return 0;
+ }
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);

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