rtc: check if __rtc_read_time was successful

BugLink: https://bugs.launchpad.net/bugs/1971497
commit 915593a7a663b2ad08b895a5f3ba8b19d89d4ebf upstream.

Clang static analysis reports this issue
interface.c:810:8: warning: Passed-by-value struct
  argument contains uninitialized data
  now = rtc_tm_to_ktime(tm);
      ^~~~~~~~~~~~~~~~~~~

tm is set by a successful call to __rtc_read_time()
but its return status is not checked.  Check if
it was successful before setting the enabled flag.
Move the decl of err to function scope.

Fixes: 2b2f5ff00f63 ("rtc: interface: ignore expired timers when enqueuing new timers")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220326194236.2916310-1-trix@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 5c1378d2fab3ddde1001cdce92ff7ee1afab8b10..ba345a379e262ef6a4a14674e2e1b23c86befbe7 100644 (file)
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -793,9 +793,13 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
        struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
        struct rtc_time tm;
        ktime_t now;
+       int err;
+
+       err = __rtc_read_time(rtc, &tm);
+       if (err)
+               return err;
 
        timer->enabled = 1;
-       __rtc_read_time(rtc, &tm);
        now = rtc_tm_to_ktime(tm);
 
        /* Skip over expired timers */
@@ -809,7 +813,6 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
        trace_rtc_timer_enqueue(timer);
        if (!next || ktime_before(timer->node.expires, next->expires)) {
                struct rtc_wkalrm alarm;
-               int err;
 
                alarm.time = rtc_ktime_to_tm(timer->node.expires);
                alarm.enabled = 1;