[PULL 02/18] linux-user: Fix 'clock_nanosleep()' implementation

[Laurent Vivier <laurent@vivier.eu>]

From: Filip Bozuta <Filip.Bozuta@syrmia.com>

Implementation of syscall 'clock_nanosleep()' in 'syscall.c' uses
functions 'target_to_host_timespec()' and 'host_to_target_timespec()'
to transfer the value of 'struct timespec' between target and host.
However, the implementation doesn't check whether this conversion
succeeds and thus can return an unaproppriate error instead of 'EFAULT'
that is expected. This was confirmed with the modified LTP test suite
where testcases with bad 'struct timespec' adress for 'clock_nanosleep()'
were added. This modified LTP suite can be found at:
https://github.com/bozutaf/ltp

(Patch with this new test case will be sent to LTP mailing list soon)

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200727201326.401519-1-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/syscall.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5b3fce3dc0cb..e387246d7196 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -11875,7 +11875,9 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
     case TARGET_NR_clock_nanosleep:
     {
         struct timespec ts;
-        target_to_host_timespec(&ts, arg3);
+        if (target_to_host_timespec(&ts, arg3)) {
+            return -TARGET_EFAULT;
+        }
         ret = get_errno(safe_clock_nanosleep(arg1, arg2,
                                              &ts, arg4 ? &ts : NULL));
         /*
@@ -11883,8 +11885,9 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
          * with error -TARGET_EINTR and if arg4 is not NULL and arg2 is not
          * TIMER_ABSTIME, it returns the remaining unslept time in arg4.
          */
-        if (ret == -TARGET_EINTR && arg4 && arg2 != TIMER_ABSTIME) {
-            host_to_target_timespec(arg4, &ts);
+        if (ret == -TARGET_EINTR && arg4 && arg2 != TIMER_ABSTIME &&
+            host_to_target_timespec(arg4, &ts)) {
+              return -TARGET_EFAULT;
         }
 
         return ret;
-- 
2.26.2