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(+)
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; } /*
The following commit has been merged into the timers/urgent branch of tip:
Commit-ID: 06764291690f8650a9f96dea42cc0dd4138d47d5 Gitweb: https://git.kernel.org/tip/06764291690f8650a9f96dea42cc0dd4138d47d5 Author: Andrei Vagin avagin@gmail.com AuthorDate: Thu, 15 Oct 2020 00:29:08 -07:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Thu, 15 Oct 2020 11:24:04 +02:00
futex: Adjust futex absolute timeouts with per-timens offset
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.
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 Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20201015072909.271426-1-avagin@gmail.com
--- kernel/futex.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/futex.c b/kernel/futex.c index a587669..9ff2b8c 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; } /*
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
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