The following commit has been merged into the timers/core branch of tip: Commit-ID: b952caf2d5ca898cc10d63be7722ae7a5daca696 Gitweb: https://git.kernel.org/tip/b952caf2d5ca898cc10d63be7722ae7a5daca696 Author: Qianli Zhao <zhaoqianli@xxxxxxxxxx> AuthorDate: Thu, 13 Aug 2020 23:03:14 +08:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Thu, 24 Sep 2020 22:12:18 +02:00 timers: Mask invalid flags in do_init_timer() do_init_timer() accepts any combination of timer flags handed in by the caller without a sanity check, but only TIMER_DEFFERABLE, TIMER_PINNED and TIMER_IRQSAFE are valid. If the supplied flags have other bits set, this could result in malfunction. If bits are set in TIMER_CPUMASK the first timer usage could deference a cpu base which is outside the range of possible CPUs. If TIMER_MIGRATION is set, then the switch_timer_base() will live lock. Prevent that with a sanity check which warns when invalid flags are supplied and masks them out. [ tglx: Made it WARN_ON_ONCE() and added context to the changelog ] Signed-off-by: Qianli Zhao <zhaoqianli@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/9d79a8aa4eb56713af7379f99f062dedabcde140.1597326756.git.zhaoqianli@xxxxxxxxxx --- include/linux/timer.h | 1 + kernel/time/timer.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/include/linux/timer.h b/include/linux/timer.h index 07910ae..d10bc7e 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -67,6 +67,7 @@ struct timer_list { #define TIMER_DEFERRABLE 0x00080000 #define TIMER_PINNED 0x00100000 #define TIMER_IRQSAFE 0x00200000 +#define TIMER_INIT_FLAGS (TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE) #define TIMER_ARRAYSHIFT 22 #define TIMER_ARRAYMASK 0xFFC00000 diff --git a/kernel/time/timer.c b/kernel/time/timer.c index a16764b..25e048d 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -794,6 +794,8 @@ static void do_init_timer(struct timer_list *timer, { timer->entry.pprev = NULL; timer->function = func; + if (WARN_ON_ONCE(flags & ~TIMER_INIT_FLAGS)) + flags &= TIMER_INIT_FLAGS; timer->flags = flags | raw_smp_processor_id(); lockdep_init_map(&timer->lockdep_map, name, key, 0); }
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