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From: Andrew Morton <akpm@linux-foundation.org>
To: adobriyan@gmail.com, akpm@linux-foundation.org,
	anna.schumaker@netapp.com, arjan@linux.intel.com,
	bfields@fieldses.org, chuck.lever@oracle.com,
	davem@davemloft.net, jlayton@kernel.org, linux-mm@kvack.org,
	luto@kernel.org, mingo@kernel.org, mm-commits@vger.kernel.org,
	Nadia.Derbey@bull.net, nixiaoming@huawei.com, paulmck@kernel.org,
	semen.protsenko@linaro.org, stern@rowland.harvard.edu,
	tglx@linutronix.de, torvalds@linux-foundation.org,
	trond.myklebust@hammerspace.com, viresh.kumar@linaro.org,
	vvs@virtuozzo.com, yuehaibing@huawei.com
Subject: [patch 19/86] kernel/notifier.c: intercept duplicate registrations to avoid infinite loops
Date: Wed, 04 Dec 2019 16:50:39 -0800
Message-ID: <20191205005039.RKFvLxRvH%akpm@linux-foundation.org> (raw)
In-Reply-To: <20191204164858.fe4ed8886e34ad9f3b34ea00@linux-foundation.org>

From: Xiaoming Ni <nixiaoming@huawei.com>
Subject: 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>
---

 kernel/notifier.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/kernel/notifier.c~kernel-notifierc-intercepting-duplicate-registrations-to-avoid-infinite-loops
+++ a/kernel/notifier.c
@@ -23,7 +23,10 @@ static int notifier_chain_register(struc
 		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);
_


  parent reply index

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05  0:48 incoming Andrew Morton
2019-12-05  0:49 ` [patch 01/86] mm/kasan/common.c: fix compile error Andrew Morton
2019-12-05  0:49 ` [patch 02/86] mm: memcg/slab: wait for !root kmem_cache refcnt killing on root kmem_cache destruction Andrew Morton
2019-12-05  0:49 ` [patch 03/86] mm/vmstat: add helpers to get vmstat item names for each enum type Andrew Morton
2019-12-05  0:49 ` [patch 04/86] mm/memcontrol: use vmstat names for printing statistics Andrew Morton
2019-12-05  0:49 ` [patch 05/86] mm/memory.c: replace is_zero_pfn with is_huge_zero_pmd for thp Andrew Morton
2019-12-05  0:49 ` [patch 06/86] proc: change ->nlink under proc_subdir_lock Andrew Morton
2019-12-05  0:50 ` [patch 07/86] fs/proc/generic.c: delete useless "len" variable Andrew Morton
2019-12-05  0:50 ` [patch 08/86] fs/proc/internal.h: shuffle "struct pde_opener" Andrew Morton
2019-12-05  0:50 ` [patch 09/86] include/linux/proc_fs.h: fix confusing macro arg name Andrew Morton
2019-12-05  0:50 ` [patch 10/86] fs/proc/Kconfig: fix indentation Andrew Morton
2019-12-05  0:50 ` [patch 11/86] include/linux/sysctl.h: inline braces for ctl_table and ctl_table_header Andrew Morton
2019-12-05  0:50 ` [patch 12/86] .gitattributes: use 'dts' diff driver for dts files Andrew Morton
2019-12-05  1:00   ` Frank Rowand
2019-12-05  0:50 ` [patch 13/86] linux/build_bug.h: change type to int Andrew Morton
2019-12-05  0:50 ` [patch 14/86] linux/scc.h: make uapi linux/scc.h self-contained Andrew Morton
2019-12-05  0:50 ` [patch 15/86] arch/Kconfig: fix indentation Andrew Morton
2019-12-05  0:50 ` [patch 16/86] scripts/get_maintainer.pl: add signatures from Fixes: <badcommit> lines in commit message Andrew Morton
2019-12-05  0:50 ` [patch 17/86] kernel.h: update comment about simple_strto<foo>() functions Andrew Morton
2019-12-05  0:50 ` [patch 18/86] auxdisplay: charlcd: deduplicate simple_strtoul() Andrew Morton
2019-12-05  0:50 ` Andrew Morton [this message]
2019-12-05  0:50 ` [patch 20/86] kernel/notifier.c: remove notifier_chain_cond_register() Andrew Morton
2019-12-05  0:50 ` [patch 21/86] kernel/notifier.c: remove blocking_notifier_chain_cond_register() Andrew Morton
2019-12-05  0:50 ` [patch 22/86] kernel/profile.c: use cpumask_available to check for NULL cpumask Andrew Morton
2019-12-05  0:50 ` [patch 23/86] kernel/sys.c: avoid copying possible padding bytes in copy_to_user Andrew Morton
2019-12-05  0:50 ` [patch 24/86] bitops: introduce the for_each_set_clump8 macro Andrew Morton
2019-12-05  0:51 ` [patch 25/86] lib/test_bitmap.c: add for_each_set_clump8 test cases Andrew Morton
2019-12-05  0:51 ` [patch 26/86] gpio: 104-dio-48e: utilize for_each_set_clump8 macro Andrew Morton
2019-12-05  0:51 ` [patch 27/86] gpio: 104-idi-48: " Andrew Morton
2019-12-05  0:51 ` [patch 28/86] gpio: gpio-mm: " Andrew Morton
2019-12-05  0:51 ` [patch 29/86] gpio: ws16c48: " Andrew Morton
2019-12-05  0:51 ` [patch 30/86] gpio: pci-idio-16: " Andrew Morton
2019-12-05  0:51 ` [patch 31/86] gpio: pcie-idio-24: " Andrew Morton
2019-12-05  0:51 ` [patch 32/86] gpio: uniphier: " Andrew Morton
2019-12-05  0:51 ` [patch 33/86] gpio: 74x164: utilize the " Andrew Morton
2019-12-05  0:51 ` [patch 34/86] thermal: intel: intel_soc_dts_iosf: Utilize " Andrew Morton
2019-12-05  0:51 ` [patch 35/86] gpio: pisosr: utilize the " Andrew Morton
2019-12-05  0:51 ` [patch 36/86] gpio: max3191x: " Andrew Morton
2019-12-05  0:51 ` [patch 37/86] gpio: pca953x: " Andrew Morton
2019-12-05  0:51 ` [patch 38/86] lib/rbtree: set successor's parent unconditionally Andrew Morton
2019-12-05  0:51 ` [patch 39/86] lib/rbtree: get successor's color directly Andrew Morton
2019-12-05  0:51 ` [patch 40/86] lib/test_meminit.c: add bulk alloc/free tests Andrew Morton
2019-12-05  0:51 ` [patch 41/86] lib/math/rational.c: fix possible incorrect result from rational fractions helper Andrew Morton
2019-12-05  0:52 ` [patch 42/86] lib/genalloc.c: export symbol addr_in_gen_pool Andrew Morton
2019-12-05  0:52 ` [patch 43/86] lib/genalloc.c: rename addr_in_gen_pool to gen_pool_has_addr Andrew Morton
2019-12-05  0:52 ` [patch 44/86] checkpatch: improve ignoring CamelCase SI style variants like mA Andrew Morton
2019-12-05  0:52 ` [patch 45/86] checkpatch: reduce is_maintained_obsolete lookup runtime Andrew Morton
2019-12-05  0:52 ` [patch 46/86] epoll: simplify ep_poll_safewake() for CONFIG_DEBUG_LOCK_ALLOC Andrew Morton
2019-12-05  0:52 ` [patch 47/86] fs/epoll: remove unnecessary wakeups of nested epoll Andrew Morton
2019-12-05  0:52 ` [patch 48/86] selftests: add epoll selftests Andrew Morton
2019-12-05  0:52 ` [patch 49/86] fs/binfmt_elf.c: delete unused "interp_map_addr" argument Andrew Morton
2019-12-05  0:52 ` [patch 50/86] fs/binfmt_elf.c: extract elf_read() function Andrew Morton
2019-12-05  0:52 ` [patch 51/86] init/Kconfig: fix indentation Andrew Morton
2019-12-05  0:52 ` [patch 52/86] drivers/rapidio/rio-driver.c: fix missing include of <linux/rio_drv.h> Andrew Morton
2019-12-05  0:52 ` [patch 53/86] drivers/rapidio/rio-access.c: " Andrew Morton
2019-12-05  0:52 ` [patch 54/86] drm: limit to INT_MAX in create_blob ioctl Andrew Morton
2019-12-05  0:52 ` [patch 55/86] uaccess: disallow > INT_MAX copy sizes Andrew Morton
2019-12-05  0:52 ` [patch 56/86] kcov: remote coverage support Andrew Morton
2019-12-05  0:52 ` [patch 57/86] usb, kcov: collect coverage from hub_event Andrew Morton
2019-12-05  0:52 ` [patch 58/86] vhost, kcov: collect coverage from vhost_worker Andrew Morton
2019-12-05  0:52 ` [patch 59/86] lib/ubsan: don't serialize UBSAN report Andrew Morton
2019-12-05  0:52 ` [patch 60/86] arch: ipcbuf.h: make uapi asm/ipcbuf.h self-contained Andrew Morton
2019-12-05  0:53 ` [patch 61/86] arch: msgbuf.h: make uapi asm/msgbuf.h self-contained Andrew Morton
2019-12-05  0:53 ` [patch 62/86] arch: sembuf.h: make uapi asm/sembuf.h self-contained Andrew Morton
2019-12-05  0:53 ` [patch 63/86] lib/test_bitmap: force argument of bitmap_parselist_user() to proper address space Andrew Morton
2019-12-05  0:53 ` [patch 64/86] lib/test_bitmap: undefine macros after use Andrew Morton
2019-12-05  0:53 ` [patch 65/86] lib/test_bitmap: name EXP_BYTES properly Andrew Morton
2019-12-05  0:53 ` [patch 66/86] lib/test_bitmap: rename exp to exp1 to avoid ambiguous name Andrew Morton
2019-12-05  0:53 ` [patch 67/86] lib/test_bitmap: move exp1 and exp2 upper for others to use Andrew Morton
2019-12-05  0:53 ` [patch 68/86] lib/test_bitmap: fix comment about this file Andrew Morton
2019-12-05  0:53 ` [patch 69/86] lib/bitmap: introduce bitmap_replace() helper Andrew Morton
2019-12-05  0:53 ` [patch 70/86] gpio: pca953x: remove redundant variable and check in IRQ handler Andrew Morton
2019-12-05  0:53 ` [patch 71/86] gpio: pca953x: use input from regs structure in pca953x_irq_pending() Andrew Morton
2019-12-05  0:53 ` [patch 72/86] gpio: pca953x: convert to use bitmap API Andrew Morton
2019-12-05  0:53 ` [patch 73/86] gpio: pca953x: tighten up indentation Andrew Morton
2019-12-05  0:53 ` [patch 74/86] alpha: use pgtable-nopud instead of 4level-fixup Andrew Morton
2019-12-05  0:53 ` [patch 75/86] arm: nommu: " Andrew Morton
2019-12-05  0:53 ` [patch 76/86] c6x: " Andrew Morton
2019-12-05  0:53 ` [patch 77/86] m68k: nommu: " Andrew Morton
2019-12-05  0:53 ` [patch 78/86] m68k: mm: use pgtable-nopXd " Andrew Morton
2019-12-05  0:54 ` [patch 79/86] microblaze: use pgtable-nopmd " Andrew Morton
2019-12-05  0:54 ` [patch 80/86] nds32: " Andrew Morton
2019-12-05  0:54 ` [patch 81/86] parisc: use pgtable-nopXd " Andrew Morton
2019-12-05  0:54 ` [patch 82/86] parisc/hugetlb: " Andrew Morton
2019-12-05  0:54 ` [patch 83/86] sparc32: use pgtable-nopud " Andrew Morton
2019-12-05  0:54 ` [patch 84/86] um: remove unused pxx_offset_proc() and addr_pte() functions Andrew Morton
2019-12-05  0:54 ` [patch 85/86] um: add support for folded p4d page tables Andrew Morton
2019-12-05  0:54 ` [patch 86/86] mm: remove __ARCH_HAS_4LEVEL_HACK and include/asm-generic/4level-fixup.h Andrew Morton

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