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timers: Mask invalid flags in do_init_timer()

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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@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/9d79a8aa4eb56713af7379f99f062dedabcde140.1597326756.git.zhaoqianli@xiaomi.com
This commit is contained in:
Qianli Zhao
2020-08-13 23:03:14 +08:00
committed by Thomas Gleixner
parent ec02821c1d
commit b952caf2d5
2 changed files with 3 additions and 0 deletions
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1
include/linux/timer.h
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@@ -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