From 29f1b2b0fecfae69e31833836f1da3136696eee5 Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Thu, 28 Dec 2017 22:11:36 -0500 Subject: posix-timers: Prevent UB from shifting negative signed value Shifting a negative signed number is undefined behavior. Looking at the macros MAKE_PROCESS_CPUCLOCK and FD_TO_CLOCKID, it seems that the subexpression: (~(clockid_t) (pid) << 3) where clockid_t resolves to a signed int, which once negated, is undefined behavior to shift the value of if the results thus far are negative. It was further suggested to make these macros into inline functions. Suggested-by: Thomas Gleixner Signed-off-by: Nick Desaulniers Signed-off-by: Thomas Gleixner Cc: Dimitri Sivanich Cc: Frederic Weisbecker Cc: Al Viro Cc: linux-kselftest@vger.kernel.org Cc: Shuah Khan Cc: Deepa Dinamani Link: https://lkml.kernel.org/r/1514517100-18051-1-git-send-email-nick.desaulniers@gmail.com --- kernel/time/posix-clock.c | 2 +- kernel/time/posix-cpu-timers.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c index 17cdc554c9fe..cc91d90abd84 100644 --- a/kernel/time/posix-clock.c +++ b/kernel/time/posix-clock.c @@ -216,7 +216,7 @@ struct posix_clock_desc { static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) { - struct file *fp = fget(CLOCKID_TO_FD(id)); + struct file *fp = fget(clockid_to_fd(id)); int err = -EINVAL; if (!fp) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 1f27887aa194..cef79ca5bbd5 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1363,8 +1363,8 @@ static long posix_cpu_nsleep_restart(struct restart_block *restart_block) return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t); } -#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED) -#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED) +#define PROCESS_CLOCK make_process_cpuclock(0, CPUCLOCK_SCHED) +#define THREAD_CLOCK make_thread_cpuclock(0, CPUCLOCK_SCHED) static int process_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp) -- cgit v1.2.3