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Subject[patch 26/38] hrtimer: fix *rmtp/restarts handling in compat_sys_nanosleep()
2.6.24-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Oleg Nesterov <oleg@tv-sign.ru>

commit 416529374b4793ba2d2e97e736d108a2e0f3ef07

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.

Introduced by commit c70878b4e0b6cf8d2f1e46319e48e821ef4a8aba
hrtimer: hook compat_sys_nanosleep up to high res timer code

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@tv-sign.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Pavel Emelyanov <xemul@sw.ru>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Toyo Abe <toyoa@mvista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>


---
kernel/compat.c | 44 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)

--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -40,10 +40,36 @@ 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 compat_timespec __user *rmtp;
+ struct timespec rmt;
+ mm_segment_t oldfs;
+ long ret;
+
+ rmtp = (struct compat_timespec __user *)(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 +78,21 @@ asmlinkage long compat_sys_nanosleep(str
if (!timespec_valid(&tu))
return -EINVAL;

- ret = hrtimer_nanosleep(&tu, rmtp ? &rmt : NULL, HRTIMER_MODE_REL,
- CLOCK_MONOTONIC);
+ oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = hrtimer_nanosleep(&tu,
+ rmtp ? (struct timespec __user *)&rmt : NULL,
+ HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+ set_fs(oldfs);
+
+ if (ret) {
+ struct restart_block *restart
+ = &current_thread_info()->restart_block;
+
+ restart->fn = compat_nanosleep_restart;
+ restart->arg1 = (unsigned long)rmtp;

- if (ret && rmtp) {
- if (put_compat_timespec(&rmt, rmtp))
+ if (rmtp && put_compat_timespec(&rmt, rmtp))
return -EFAULT;
}

--


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