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Message-ID: <20080201173531.GA26540@tv-sign.ru>
Date: Fri, 1 Feb 2008 20:35:31 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Ingo Molnar <mingo@...e.hu>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Alexey Dobriyan <adobriyan@...ru>,
Pavel Emelyanov <xemul@...ru>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Toyo Abe <toyoa@...sta.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] compat_sys_nanosleep: fix *rmtp/restarts handling
On 02/01, Oleg Nesterov wrote:
>
> Hopefully this was the last bug, updated patch below.
That was a joke.
Contrary to my expectations, the patch didn't suffer (I hope) from the
buggy "PATCH 1/1". But it can be simplified a bit, no need to check ret
twice.
[PATCH 3/5] compat_sys_nanosleep: fix *rmtp/restarts handling
COMPLETELY UNTESTED.
Spotted by Pavel Emelyanov and Alexey Dobriyan.
compat_sys_nanosleep() implicitly uses hrtimer_nanosleep_restart(), this can't
work. Make a suitable compat_nanosleep_restart() helper.
Also, set ->addr_limit = KERNEL_DS before doing hrtimer_nanosleep(), this func
was changed by the previous patch and now takes the "__user *" parameter.
Thanks to Ingo Molnar for fixing the bug in this patch.
Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
--- MM/kernel/compat.c~x3_COMPAT_NANOSLEEP 2008-02-01 18:54:44.000000000 +0300
+++ MM/kernel/compat.c 2008-02-01 20:24:52.000000000 +0300
@@ -40,10 +40,35 @@ int put_compat_timespec(const struct tim
__put_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
}
+static long compat_nanosleep_restart(struct restart_block *restart)
+{
+ struct timespec rmt;
+ mm_segment_t oldfs;
+ long ret;
+ struct compat_timespec *rmtp = (struct compat_timespec *)(restart->arg1);
+
+ restart->arg1 = (unsigned long)&rmt;
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = hrtimer_nanosleep_restart(restart);
+ set_fs(oldfs);
+
+ if (ret) {
+ restart->fn = compat_nanosleep_restart;
+ restart->arg1 = (unsigned long)rmtp;
+
+ if (rmtp && put_compat_timespec(&rmt, rmtp))
+ return -EFAULT;
+ }
+
+ return ret;
+}
+
asmlinkage long compat_sys_nanosleep(struct compat_timespec __user *rqtp,
struct compat_timespec __user *rmtp)
{
struct timespec tu, rmt;
+ mm_segment_t oldfs;
long ret;
if (get_compat_timespec(&tu, rqtp))
@@ -52,11 +77,20 @@ asmlinkage long compat_sys_nanosleep(str
if (!timespec_valid(&tu))
return -EINVAL;
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
ret = hrtimer_nanosleep(&tu, rmtp ? &rmt : NULL, HRTIMER_MODE_REL,
CLOCK_MONOTONIC);
+ set_fs(oldfs);
- if (ret && rmtp) {
- if (put_compat_timespec(&rmt, rmtp))
+ if (ret) {
+ struct restart_block *restart
+ = ¤t_thread_info()->restart_block;
+
+ restart->fn = compat_nanosleep_restart;
+ restart->arg1 = (unsigned long)rmtp;
+
+ if (rmtp && put_compat_timespec(&rmt, rmtp))
return -EFAULT;
}
--
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