hrtimer: fix *rmtp/restarts handling in compat_sys_nanosleep()

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Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=416529374b4793ba2d2e97e736d108a2e0f3ef07
Commit:     416529374b4793ba2d2e97e736d108a2e0f3ef07
Parent:     080344b98805553f9b01de0f59a41b1533036d8d
Author:     Oleg Nesterov <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 1 20:35:31 2008 +0300
Committer:  Thomas Gleixner <[EMAIL PROTECTED]>
CommitDate: Sun Feb 10 10:48:03 2008 +0100

    hrtimer: fix *rmtp/restarts handling in compat_sys_nanosleep()
    
    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 <[EMAIL PROTECTED]>
    Cc: Andrew Morton <[EMAIL PROTECTED]>
    Cc: Alexey Dobriyan <[EMAIL PROTECTED]>
    Cc: Pavel Emelyanov <[EMAIL PROTECTED]>
    Cc: Peter Zijlstra <[EMAIL PROTECTED]>
    Cc: Toyo Abe <[EMAIL PROTECTED]>
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
 kernel/compat.c |   44 ++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/kernel/compat.c b/kernel/compat.c
index 42a1ed4..f2a2975 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -40,10 +40,36 @@ int put_compat_timespec(const struct timespec *ts, struct 
compat_timespec __user
                        __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(struct compat_timespec 
__user *rqtp,
        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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