From: Zeng Tao prime.zeng@hisilicon.com
commit cb47755725da7b90fecbb2aa82ac3b24a7adb89b upstream.
UBSAN reports:
Undefined behaviour in ./include/linux/time64.h:127:27 signed integer overflow: 17179869187 * 1000000000 cannot be represented in type 'long long int' Call Trace: timespec64_to_ns include/linux/time64.h:127 [inline] set_cpu_itimer+0x65c/0x880 kernel/time/itimer.c:180 do_setitimer+0x8e/0x740 kernel/time/itimer.c:245 __x64_sys_setitimer+0x14c/0x2c0 kernel/time/itimer.c:336 do_syscall_64+0xa1/0x540 arch/x86/entry/common.c:295
Commit bd40a175769d ("y2038: itimer: change implementation to timespec64") replaced the original conversion which handled time clamping correctly with timespec64_to_ns() which has no overflow protection.
Fix it in timespec64_to_ns() as this is not necessarily limited to the usage in itimers.
[ tglx: Added comment and adjusted the fixes tag ]
Fixes: 361a3bf00582 ("time64: Add time64.h header and define struct timespec64") Signed-off-by: Zeng Tao prime.zeng@hisilicon.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Arnd Bergmann arnd@arndb.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/1598952616-6416-1-git-send-email-prime.zeng@hisili... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/time64.h | 4 ++++ kernel/time/itimer.c | 4 ---- 2 files changed, 4 insertions(+), 4 deletions(-)
--- a/include/linux/time64.h +++ b/include/linux/time64.h @@ -124,6 +124,10 @@ static inline bool timespec64_valid_sett */ static inline s64 timespec64_to_ns(const struct timespec64 *ts) { + /* Prevent multiplication overflow */ + if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX) + return KTIME_MAX; + return ((s64) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec; }
--- a/kernel/time/itimer.c +++ b/kernel/time/itimer.c @@ -172,10 +172,6 @@ static void set_cpu_itimer(struct task_s u64 oval, nval, ointerval, ninterval; struct cpu_itimer *it = &tsk->signal->it[clock_id];
- /* - * Use the to_ktime conversion because that clamps the maximum - * value to KTIME_MAX and avoid multiplication overflows. - */ nval = timespec64_to_ns(&value->it_value); ninterval = timespec64_to_ns(&value->it_interval);