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authorMike Waychison <mikew@google.com>2011-08-12 21:04:30 +0000
committerJohn Stultz <john.stultz@linaro.org>2011-08-26 17:26:35 -0700
commita7402deb324f62106566f5a95199a54c41e200ef (patch)
tree0eafe76a936eaa9f5391988d2a0021b3d0907dbb /drivers/rtc
parent938f97bcf1bdd1b681d5d14d1d7117a2e22d4434 (diff)
rtc: Initialized rtc_time->tm_isdst
Even though the Linux kernel does not use the tm_isdst field, it is exposed as part of the ABI. This field can accidentally be left initialized, which is why we currently memset buffers returned to userland in rtc_read_time. There is a case however where the field can return garbage from the stack though when using the RTC_ALM_READ ioctl on the rtc device. This ioctl invokes rtc_read_alarm, which is careful to memset the rtc_wkalrm buffer that is copied to userland, but it then uses a struct copy to assign to alarm->time given the return value from rtc_ktime_to_tm(). rtc_ktime_to_tm() is implemented by calling rtc_time_to_tm using a derivative seconds counds from ktime, but rtc_time_to_tm does not assign a value to ->tm_isdst. This results in garbage from rtc_ktime_to_tm()'s frame ending up being copied out to userland as part of the returned rtc_wkalrm. Fix this by initializing rtc_time->tm_isdst to 0 in rtc_time_to_tm. Signed-off-by: Mike Waychison <mikew@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-lib.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
index 075f1708dea..c4cf0573111 100644
--- a/drivers/rtc/rtc-lib.c
+++ b/drivers/rtc/rtc-lib.c
@@ -85,6 +85,8 @@ void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
time -= tm->tm_hour * 3600;
tm->tm_min = time / 60;
tm->tm_sec = time - tm->tm_min * 60;
+
+ tm->tm_isdst = 0;
}
EXPORT_SYMBOL(rtc_time_to_tm);