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drivers/rtc/rtc-efi.c: check for invalid data coming back from UEFI

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In particular seeing zero in eft->month is problematic, as it results in
-1 (converted to unsigned int, i.e.  yielding 0xffffffff) getting passed
to rtc_year_days(), where the value gets used as an array index
(normally resulting in a crash).  This was observed with the driver
enabled on x86 on some Fujitsu system (with possibly not up to date
firmware, but anyway).

Perhaps efi_read_alarm() should not fail if neither enabled nor pending
are set, but the returned time is invalid?

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reported-by: Raymund Will <rw@suse.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Jingoo Han <jg1.han@samsung.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Beulich 2014-08-08 14:20:09 -07:00 committed by Linus Torvalds
parent 3710f597ac
commit 6e85bab6bc
1 changed files with 27 additions and 5 deletions
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32
drivers/rtc/rtc-efi.c
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@ -17,6 +17,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/time.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
@ -48,8 +49,8 @@ compute_wday(efi_time_t *eft)
int y;
int ndays = 0;
if (eft->year < 1998) {
pr_err("EFI year < 1998, invalid date\n");
if (eft->year < EFI_RTC_EPOCH) {
pr_err("EFI year < " __stringify(EFI_RTC_EPOCH) ", invalid date\n");
return -1;
}
@ -78,19 +79,36 @@ convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
eft->timezone = EFI_UNSPECIFIED_TIMEZONE;
}
static void
static bool
convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
{
memset(wtime, 0, sizeof(*wtime));
if (eft->second >= 60)
return false;
wtime->tm_sec = eft->second;
if (eft->minute >= 60)
return false;
wtime->tm_min = eft->minute;
if (eft->hour >= 24)
return false;
wtime->tm_hour = eft->hour;
if (!eft->day || eft->day > 31)
return false;
wtime->tm_mday = eft->day;
if (!eft->month || eft->month > 12)
return false;
wtime->tm_mon = eft->month - 1;
wtime->tm_year = eft->year - 1900;
/* day of the week [0-6], Sunday=0 */
wtime->tm_wday = compute_wday(eft);
if (wtime->tm_wday < 0)
return false;
/* day in the year [1-365]*/
wtime->tm_yday = compute_yday(eft);
@ -106,6 +124,8 @@ convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
default:
wtime->tm_isdst = -1;
}
return true;
}
static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
@ -122,7 +142,8 @@ static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
if (status != EFI_SUCCESS)
return -EINVAL;
convert_from_efi_time(&eft, &wkalrm->time);
if (!convert_from_efi_time(&eft, &wkalrm->time))
return -EIO;
return rtc_valid_tm(&wkalrm->time);
}
@ -163,7 +184,8 @@ static int efi_read_time(struct device *dev, struct rtc_time *tm)
return -EINVAL;
}
convert_from_efi_time(&eft, tm);
if (!convert_from_efi_time(&eft, tm))
return -EIO;
return rtc_valid_tm(tm);
}