cputime: Prevent 32bit overflow in time[val|spec]_to_cputime()

prime-zeng · KAGA-KOKO · commit 0f26922fe5dc · 2016-02-02T15:24:38.000+01:00
The datatype __kernel_time_t is u32 on 32bit platform, so its subject to overflows in the timeval/timespec to cputime conversion. Currently the following functions are affected: 1. setitimer() 2. timer_create/timer_settime() 3. sys_clock_nanosleep This can happen on MIPS32 and ARM32 with "Full dynticks CPU time accounting" enabled, which is required for CONFIG_NO_HZ_FULL. Enforce u64 conversion to prevent the overflow. Fixes: 31c1fc8 ("ARM: Kconfig: allow full nohz CPU accounting") Signed-off-by: zengtao <prime.zeng@huawei.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: <fweisbec@gmail.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1454384314-154784-1-git-send-email-prime.zeng@huawei.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-generic/cputime_nsecs.h b/include/asm-generic/cputime_nsecs.h
@@ -75,7 +75,7 @@ typedef u64 __nocast cputime64_t;
  */
 static inline cputime_t timespec_to_cputime(const struct timespec *val)
 {
-	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
+	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
 	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
@@ -91,7 +91,8 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
  */
 static inline cputime_t timeval_to_cputime(const struct timeval *val)
 {
-	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
+	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC +
+			val->tv_usec * NSEC_PER_USEC;
 	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)

Original file line number	Diff line number	Diff line change
`@@ -75,7 +75,7 @@ typedef u64 __nocast cputime64_t;`
`75`	`75`	`*/`
`76`	`76`	`static inline cputime_t timespec_to_cputime(const struct timespec *val)`
`77`	`77`	`{`
`78`		`- u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;`
	`78`	`+ u64 ret = (u64)val->tv_sec * NSEC_PER_SEC + val->tv_nsec;`
`79`	`79`	`return (__force cputime_t) ret;`
`80`	`80`	`}`
`81`	`81`	`static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)`
`@@ -91,7 +91,8 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)`
`91`	`91`	`*/`
`92`	`92`	`static inline cputime_t timeval_to_cputime(const struct timeval *val)`
`93`	`93`	`{`
`94`		`- u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;`
	`94`	`+ u64 ret = (u64)val->tv_sec * NSEC_PER_SEC +`
	`95`	`+ val->tv_usec * NSEC_PER_USEC;`
`95`	`96`	`return (__force cputime_t) ret;`
`96`	`97`	`}`
`97`	`98`	`static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)`