lib/vsprintf: Check pointer before dereferencing in time_and_date()

[ Upstream commit 372a12bd5df0199aa234eaf8ef31ed7ecd61d40f ]

The pointer may be invalid when gets to the printf(). In particular
the time_and_date() dereferencing it in some cases without checking.

Move the check from rtc_str() to time_and_date() to cover all cases.

Fixes: 7daac5b2fdf8 ("lib/vsprintf: Print time64_t in human readable format")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://patch.msgid.link/20251110132118.4113976-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index eb0cb11d0d126f02d8884b3ebbcdcf75beb8a621..a356965c1d7348df32e7fe872d998f5b242125d7 100644 (file)
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1928,9 +1928,6 @@ char *rtc_str(char *buf, char *end, const struct rtc_time *tm,
        bool found = true;
        int count = 2;
 
-       if (check_pointer(&buf, end, tm, spec))
-               return buf;
-
        switch (fmt[count]) {
        case 'd':
                have_t = false;
@@ -1996,6 +1993,9 @@ static noinline_for_stack
 char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
                    const char *fmt)
 {
+       if (check_pointer(&buf, end, ptr, spec))
+               return buf;
+
        switch (fmt[1]) {
        case 'R':
                return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt);