Re: [PATCH 3/5] compat_sys_nanosleep: fix *rmtp/restarts handling

[Oleg Nesterov]

On 02/01, Ingo Molnar wrote:
> 
> * Oleg Nesterov <[EMAIL PROTECTED]> wrote:
> 
> > COMPLETELY UNTESTED.
> 
> FYI, build failure on x86/64:
> 
>  kernel/compat.c: In function 'compat_sys_nanosleep':
>  kernel/compat.c:90: error: 'err' undeclared (first use in this function)
>  kernel/compat.c:90: error: (Each undeclared identifier is reported only once
>  kernel/compat.c:90: error: for each function it appears in.)

Oh, thanks a lot!

Hopefully this was the last bug, updated patch below.


[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 <[EMAIL PROTECTED]>

--- MM/kernel/compat.c~3_COMPAT_NANOSLEEP       2008-02-01 14:27:16.000000000 
+0300
+++ MM/kernel/compat.c  2008-02-01 14:50:01.000000000 +0300
@@ -40,10 +40,37 @@ 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)
+{
+       long err;
+       mm_segment_t oldfs;
+       struct timespec tu;
+       struct compat_timespec *rmtp = (struct compat_timespec 
*)(restart->arg1);
+
+       restart->arg1 = (unsigned long)&tu;
+       oldfs = get_fs();
+       set_fs(KERNEL_DS);
+       err = hrtimer_nanosleep_restart(restart);
+       set_fs(oldfs);
+
+       if (err) {
+               if (rmtp && put_compat_timespec(&tu, rmtp))
+                       return -EFAULT;
+
+               if (err == -ERESTART_RESTARTBLOCK) {
+                       restart->fn = compat_nanosleep_restart;
+                       restart->arg1 = (unsigned long)rmtp;
+               }
+       }
+
+       return err;
+}
+
 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))
@@ -52,12 +79,23 @@ 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) {
+               if (rmtp && put_compat_timespec(&rmt, rmtp))
                        return -EFAULT;
+
+               if (ret == -ERESTART_RESTARTBLOCK) {
+                       struct restart_block *restart
+                               = &current_thread_info()->restart_block;
+
+                       restart->fn = compat_nanosleep_restart;
+                       restart->arg1 = (unsigned long)rmtp;
+               }
        }
 
        return ret;

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