[Qemu-trivial] [PATCH v2] linux-user/syscall.c: Free the vec[i] in failure processing code block

[Chen Gang S <gang.chen@sunrus.com.cn>]

When failure occurs during allocating vec[i], also need free all
allocated vec[i] in failure processing code block before return.

In unlock_user(), it will check vec[i].iov_base whether is NULL, so need
not check it again outside.

If error is EFAULT when "i == 0", vec[i].iov_base is NULL, then can just
skip it, so can still use "while (--i >= 0)" for the free looping.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 linux-user/syscall.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 290fdea..a66c2ae 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1873,6 +1873,11 @@ static struct iovec *lock_iovec(int type, abi_ulong target_addr,
     return vec;
 
  fail:
+    while (--i >= 0) {
+        if (tswapal(target_vec[i].iov_len) > 0) {
+            unlock_user(vec[i].iov_base, tswapal(target_vec[i].iov_base), 0);
+        }
+    }
     unlock_user(target_vec, target_addr, 0);
  fail2:
     free(vec);
-- 
1.9.3 (Apple Git-50)