[Qemu-devel] [5562] Fix iovec for the case with invalid elements (Lauro Ramos Venancio).

[Qemu-devel] [5562] Fix iovec for the case with invalid elements (Lauro Ramos Venancio).

[Andrzej Zaborowski]

Revision: 5562
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5562
Author:   balrog
Date:     2008-10-28 10:21:03 +0000 (Tue, 28 Oct 2008)

Log Message:
-----------
Fix iovec for the case with invalid elements (Lauro Ramos Venancio).

We must call the writev even if an iovec element is invalid. For
example, if the second element is invalid, the linux process the first
one.

Modified Paths:
--------------
    trunk/linux-user/syscall.c

Modified: trunk/linux-user/syscall.c
===================================================================
--- trunk/linux-user/syscall.c	2008-10-28 10:18:28 UTC (rev 5561)
+++ trunk/linux-user/syscall.c	2008-10-28 10:21:03 UTC (rev 5562)
@@ -1064,7 +1064,7 @@
 {
     struct target_iovec *target_vec;
     abi_ulong base;
-    int i, j;
+    int i;
 
     target_vec = lock_user(VERIFY_READ, target_addr, count * sizeof(struct target_iovec), 1);
     if (!target_vec)
@@ -1074,8 +1074,8 @@
         vec[i].iov_len = tswapl(target_vec[i].iov_len);
         if (vec[i].iov_len != 0) {
             vec[i].iov_base = lock_user(type, base, vec[i].iov_len, copy);
-            if (!vec[i].iov_base && vec[i].iov_len) 
-                goto fail;
+            /* Don't check lock_user return value. We must call writev even
+               if a element has invalid base address. */
         } else {
             /* zero length pointer is ignored */
             vec[i].iov_base = NULL;
@@ -1083,14 +1083,6 @@
     }
     unlock_user (target_vec, target_addr, 0);
     return 0;
- fail:
-    /* failure - unwind locks */
-    for (j = 0; j < i; j++) {
-        base = tswapl(target_vec[j].iov_base);
-        unlock_user(vec[j].iov_base, base, 0);
-    }
-    unlock_user (target_vec, target_addr, 0);
-    return -TARGET_EFAULT;
 }
 
 static abi_long unlock_iovec(struct iovec *vec, abi_ulong target_addr,
@@ -1104,8 +1096,10 @@
     if (!target_vec)
         return -TARGET_EFAULT;
     for(i = 0;i < count; i++) {
-        base = tswapl(target_vec[i].iov_base);
-        unlock_user(vec[i].iov_base, base, copy ? vec[i].iov_len : 0);
+        if (target_vec[i].iov_base) {
+            base = tswapl(target_vec[i].iov_base);
+            unlock_user(vec[i].iov_base, base, copy ? vec[i].iov_len : 0);
+        }
     }
     unlock_user (target_vec, target_addr, 0);