2020-10-15 18:30:16

by Andrei Vagin

Subject: [PATCH 1/2 v2] futex: adjust a futex timeout with a 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.

Cc: <[email protected]>
Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets")
Reported-by: Hans van der Laan <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>
---

v2:
* check FUTEX_CLOCK_REALTIME properly
* fix futex_time32 too

kernel/futex.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index a5876694a60e..32056d2d4171 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 (!(op & FUTEX_CLOCK_REALTIME))
+ t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
tp = &t;
}
/*
@@ -3989,6 +3992,8 @@ SYSCALL_DEFINE6(futex_time32, 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 (!(op & FUTEX_CLOCK_REALTIME))
+ t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
tp = &t;
}
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
--
2.26.2

2020-10-21 06:11:16

by tip-bot2 for Alexey Makhalov

Subject: [tip: timers/urgent] futex: Adjust absolute futex timeouts with per time namespace offset

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID: c2f7d08cccf4af2ce6992feaabb9e68e4ae0bff3
Gitweb: https://git.kernel.org/tip/c2f7d08cccf4af2ce6992feaabb9e68e4ae0bff3
Author: Andrei Vagin <[email protected]>
AuthorDate: Thu, 15 Oct 2020 09:00:19 -07:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Tue, 20 Oct 2020 17:02:57 +02:00

futex: Adjust absolute futex timeouts with per time namespace offset

For all commands except FUTEX_WAIT, the 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 <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Dmitry Safonov <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
kernel/futex.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index 680854d..be68ac0 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 (!(op & FUTEX_CLOCK_REALTIME))
+ t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
tp = &t;
}
/*
@@ -3989,6 +3992,8 @@ SYSCALL_DEFINE6(futex_time32, 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 (!(op & FUTEX_CLOCK_REALTIME))
+ t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
tp = &t;
}
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||