On Wed, Nov 13, 2019 at 10:53 PM Thomas Gleixner [off-list ref] wrote:
On Fri, 8 Nov 2019, Arnd Bergmann wrote:
quoted
-SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
+SYSCALL_DEFINE2(settimeofday, struct __kernel_old_timeval __user *, tv,
struct timezone __user *, tz)
{
struct timespec64 new_ts;
- struct timeval user_tv;
struct timezone new_tz;
if (tv) {
- if (copy_from_user(&user_tv, tv, sizeof(*tv)))
+ if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
+ get_user(new_ts.tv_nsec, &tv->tv_usec))
return -EFAULT;
How is that supposed to be correct on a 32bit kernel?
I don't see the problem you are referring to. This should behave the
same way on a 32-bit kernel and on a 64-bit kernel, sign-extending
the tv_sec field, and copying the user tv_usec field into the
kernel tv_nsec, to be multiplied by 1000 a few lines later.
Am I missing something?
quoted
- if (!timeval_valid(&user_tv))
+ if (tv->tv_usec > USEC_PER_SEC)
return -EINVAL;
That's incomplete:
static inline bool timeval_valid(const struct timeval *tv)
{
/* Dates before 1970 are bogus */
if (tv->tv_sec < 0)
return false;
/* Can't have more microseconds then a second */
if (tv->tv_usec < 0 || tv->tv_usec >= USEC_PER_SEC)
return false;
return true;
}
My idea was to not duplicate the range check that is done
in do_sys_settimeofday64() and again in do_settimeofday64:
if (!timespec64_valid_settod(ts))
return -EINVAL;
The only check we should need in addition to this is to ensure
that passing an invalid tv_usec number doesn't become an
unexpectedly valid tv_nsec after the multiplication.
I agree the patch looks like I'm missing a check here, but
the code after the patch appears clear enough to me.
Arnd
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