| Message ID | 20201015072909.271426-1-avagin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] futex: adjust a futex timeout with a per-timens offset | expand |
On 10/15/20 8:29 AM, Andrei Vagin wrote: > For all commands except FUTEX_WAIT, timeout is interpreted as an > absolute value. This absolute value is inside the task's time namespace > and has to be converted to the host's time. > > Cc: <stable@vger.kernel.org> > Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets") > Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl> > Signed-off-by: Andrei Vagin <avagin@gmail.com>[..] > @@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, > t = timespec64_to_ktime(ts); > if (cmd == FUTEX_WAIT) > t = ktime_add_safe(ktime_get(), t); > + else if (!(cmd & FUTEX_CLOCK_REALTIME)) > + t = timens_ktime_to_host(CLOCK_MONOTONIC, t); Err, it probably should be : else if (!(op & FUTEX_CLOCK_REALTIME)) And there's also : SYSCALL_DEFINE6(futex_time32, ...) which wants to be patched. Thanks, Dmitry
On Thu, Oct 15 2020 at 14:26, Dmitry Safonov wrote: > On 10/15/20 8:29 AM, Andrei Vagin wrote: >> For all commands except FUTEX_WAIT, timeout is interpreted as an >> absolute value. This absolute value is inside the task's time namespace >> and has to be converted to the host's time. >> >> Cc: <stable@vger.kernel.org> >> Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets") >> Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl> >> Signed-off-by: Andrei Vagin <avagin@gmail.com>[..] >> @@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, >> t = timespec64_to_ktime(ts); >> if (cmd == FUTEX_WAIT) >> t = ktime_add_safe(ktime_get(), t); >> + else if (!(cmd & FUTEX_CLOCK_REALTIME)) >> + t = timens_ktime_to_host(CLOCK_MONOTONIC, t); > > Err, it probably should be > : else if (!(op & FUTEX_CLOCK_REALTIME)) Duh, you are right. I stared at it for a while and did not spot it. > And there's also > : SYSCALL_DEFINE6(futex_time32, ...) > which wants to be patched. Indeed. I zapped the commits. Thanks, tglx
On Thu, Oct 15, 2020 at 04:13:42PM +0200, Thomas Gleixner wrote: > On Thu, Oct 15 2020 at 14:26, Dmitry Safonov wrote: > > > On 10/15/20 8:29 AM, Andrei Vagin wrote: > >> For all commands except FUTEX_WAIT, timeout is interpreted as an > >> absolute value. This absolute value is inside the task's time namespace > >> and has to be converted to the host's time. > >> > >> Cc: <stable@vger.kernel.org> > >> Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets") > >> Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl> > >> Signed-off-by: Andrei Vagin <avagin@gmail.com>[..] > >> @@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, > >> t = timespec64_to_ktime(ts); > >> if (cmd == FUTEX_WAIT) > >> t = ktime_add_safe(ktime_get(), t); > >> + else if (!(cmd & FUTEX_CLOCK_REALTIME)) > >> + t = timens_ktime_to_host(CLOCK_MONOTONIC, t); > > > > Err, it probably should be > > : else if (!(op & FUTEX_CLOCK_REALTIME)) Dmitry, thank you for catching this. > > Duh, you are right. I stared at it for a while and did not spot it. > > > And there's also > > : SYSCALL_DEFINE6(futex_time32, ...) > > which wants to be patched. > > Indeed. I zapped the commits. I sent a new version. This time, I extended the test to check FUTEX_CLOCK_REALTIME and I compiled and run the compat version. Everything works as it should be. Thanks, Andrei
diff --git a/kernel/futex.c b/kernel/futex.c index a5876694a60e..9ff2b8c5a506 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -39,6 +39,7 @@ #include <linux/freezer.h> #include <linux/memblock.h> #include <linux/fault-inject.h> +#include <linux/time_namespace.h> #include <asm/futex.h> @@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, t = timespec64_to_ktime(ts); if (cmd == FUTEX_WAIT) t = ktime_add_safe(ktime_get(), t); + else if (!(cmd & FUTEX_CLOCK_REALTIME)) + t = timens_ktime_to_host(CLOCK_MONOTONIC, t); tp = &t; } /*
For all commands except FUTEX_WAIT, timeout is interpreted as an absolute value. This absolute value is inside the task's time namespace and has to be converted to the host's time. Cc: <stable@vger.kernel.org> Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets") Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl> Signed-off-by: Andrei Vagin <avagin@gmail.com> --- kernel/futex.c | 3 +++ 1 file changed, 3 insertions(+)