Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753189AbeADOER (ORCPT + 1 other); Thu, 4 Jan 2018 09:04:17 -0500 Received: from terminus.zytor.com ([65.50.211.136]:47265 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753157AbeADOEP (ORCPT ); Thu, 4 Jan 2018 09:04:15 -0500 Date: Thu, 4 Jan 2018 06:01:56 -0800 From: tip-bot for Nick Desaulniers Message-ID: Cc: hpa@zytor.com, sivanich@hpe.com, mingo@kernel.org, viro@zeniv.linux.org.uk, shuah@kernel.org, tglx@linutronix.de, fweisbec@gmail.com, nick.desaulniers@gmail.com, linux-kernel@vger.kernel.org, deepa.kernel@gmail.com Reply-To: deepa.kernel@gmail.com, linux-kernel@vger.kernel.org, nick.desaulniers@gmail.com, fweisbec@gmail.com, tglx@linutronix.de, shuah@kernel.org, viro@zeniv.linux.org.uk, hpa@zytor.com, mingo@kernel.org, sivanich@hpe.com In-Reply-To: <1514517100-18051-1-git-send-email-nick.desaulniers@gmail.com> References: <1514517100-18051-1-git-send-email-nick.desaulniers@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] posix-timers: Prevent UB from shifting negative signed value Git-Commit-ID: 29f1b2b0fecfae69e31833836f1da3136696eee5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Commit-ID: 29f1b2b0fecfae69e31833836f1da3136696eee5 Gitweb: https://git.kernel.org/tip/29f1b2b0fecfae69e31833836f1da3136696eee5 Author: Nick Desaulniers AuthorDate: Thu, 28 Dec 2017 22:11:36 -0500 Committer: Thomas Gleixner CommitDate: Thu, 4 Jan 2018 14:57:10 +0100 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 --- include/linux/posix-timers.h | 25 +++++++++++++++++++------ kernel/time/posix-clock.c | 2 +- kernel/time/posix-cpu-timers.c | 4 ++-- tools/testing/selftests/ptp/testptp.c | 4 +--- 4 files changed, 23 insertions(+), 12 deletions(-) diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index 672c4f3..c85704f 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -42,13 +42,26 @@ struct cpu_timer_list { #define CLOCKFD CPUCLOCK_MAX #define CLOCKFD_MASK (CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK) -#define MAKE_PROCESS_CPUCLOCK(pid, clock) \ - ((~(clockid_t) (pid) << 3) | (clockid_t) (clock)) -#define MAKE_THREAD_CPUCLOCK(tid, clock) \ - MAKE_PROCESS_CPUCLOCK((tid), (clock) | CPUCLOCK_PERTHREAD_MASK) +static inline clockid_t make_process_cpuclock(const unsigned int pid, + const clockid_t clock) +{ + return ((~pid) << 3) | clock; +} +static inline clockid_t make_thread_cpuclock(const unsigned int tid, + const clockid_t clock) +{ + return make_process_cpuclock(tid, clock | CPUCLOCK_PERTHREAD_MASK); +} -#define FD_TO_CLOCKID(fd) ((~(clockid_t) (fd) << 3) | CLOCKFD) -#define CLOCKID_TO_FD(clk) ((unsigned int) ~((clk) >> 3)) +static inline clockid_t fd_to_clockid(const int fd) +{ + return make_process_cpuclock((unsigned int) fd, CLOCKFD); +} + +static inline int clockid_to_fd(const clockid_t clk) +{ + return ~(clk >> 3); +} #define REQUEUE_PENDING 1 diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c index 17cdc55..cc91d90 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 1f27887a..cef79ca 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) diff --git a/tools/testing/selftests/ptp/testptp.c b/tools/testing/selftests/ptp/testptp.c index 5d2eae1..a5d8f0a 100644 --- a/tools/testing/selftests/ptp/testptp.c +++ b/tools/testing/selftests/ptp/testptp.c @@ -60,9 +60,7 @@ static int clock_adjtime(clockid_t id, struct timex *tx) static clockid_t get_clockid(int fd) { #define CLOCKFD 3 -#define FD_TO_CLOCKID(fd) ((~(clockid_t) (fd) << 3) | CLOCKFD) - - return FD_TO_CLOCKID(fd); + return (((unsigned int) ~fd) << 3) | CLOCKFD; } static void handle_alarm(int s)