[Qemu-devel] RFC: [11/11] EFAULT patch

[Qemu-devel] RFC: [11/11] EFAULT patch

[Stuart Anderson]

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Last, but not least, this part contains the changes to the function that
read and write iovec structures. This part will require one more pass to
eliminate the inner calls to the old API.


                                 Stuart

Stuart R. Anderson                               anderson@netsweng.com
Network & Software Engineering                   http://www.netsweng.com/
1024D/37A79149:                                  0791 D3B8 9A4C 2CDC A31F
                                                  BD03 0A62 E534 37A7 9149

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Index: qemu/linux-user/syscall.c
===================================================================
--- qemu.orig/linux-user/syscall.c	2007-09-16 16:03:46.000000000 -0400
+++ qemu/linux-user/syscall.c	2007-09-16 16:06:36.000000000 -0400
@@ -855,7 +855,7 @@
     return ret;
 }
 
-static void lock_iovec(struct iovec *vec, target_ulong target_addr,
+static long copy_from_iovec(struct iovec *vec, target_ulong target_addr,
                        int count, int copy)
 {
     struct target_iovec *target_vec;
@@ -863,15 +863,18 @@
     int i;
 
     target_vec = lock_user(target_addr, count * sizeof(struct target_iovec), 1);
+    if( !access_ok(VERIFY_READ, target_vec, count * sizeof(struct target_iovec)) ) return -1;
     for(i = 0;i < count; i++) {
         base = tswapl(target_vec[i].iov_base);
         vec[i].iov_len = tswapl(target_vec[i].iov_len);
         vec[i].iov_base = lock_user(base, vec[i].iov_len, copy);
     }
     unlock_user (target_vec, target_addr, 0);
+
+    return 0;
 }
 
-static void unlock_iovec(struct iovec *vec, target_ulong target_addr,
+static long copy_to_iovec(struct iovec *vec, target_ulong target_addr,
                          int count, int copy)
 {
     struct target_iovec *target_vec;
@@ -879,11 +882,14 @@
     int i;
 
     target_vec = lock_user(target_addr, count * sizeof(struct target_iovec), 1);
+    if( !access_ok(VERIFY_WRITE, target_vec, count * sizeof(struct target_iovec)) ) return -1;
     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);
     }
     unlock_user (target_vec, target_addr, 0);
+
+    return 0;
 }
 
 static long do_socket(int domain, int type, int protocol)
@@ -959,7 +965,7 @@
     count = tswapl(msgp->msg_iovlen);
     vec = alloca(count * sizeof(struct iovec));
     target_vec = tswapl(msgp->msg_iov);
-    lock_iovec(vec, target_vec, count, send);
+    if( copy_from_iovec(vec, target_vec, count, send) ) return -EFAULT;
     msg.msg_iovlen = count;
     msg.msg_iov = vec;
     
@@ -971,7 +977,7 @@
         if (!is_error(ret))
             host_to_target_cmsg(msgp, &msg);
     }
-    unlock_iovec(vec, target_vec, count, !send);
+    if( copy_to_iovec(vec, target_vec, count, !send) ) return -EFAULT;
     return ret;
 }
 
@@ -3913,9 +3919,9 @@
             struct iovec *vec;
 
             vec = alloca(count * sizeof(struct iovec));
-            lock_iovec(vec, arg2, count, 0);
+            if( copy_from_iovec(vec, arg2, count, 0) ) return -EFAULT;
             ret = get_errno(readv(arg1, vec, count));
-            unlock_iovec(vec, arg2, count, 1);
+            if( copy_to_iovec(vec, arg2, count, 1) ) return -EFAULT;
         }
         break;
     case TARGET_NR_writev:
@@ -3924,9 +3930,9 @@
             struct iovec *vec;
 
             vec = alloca(count * sizeof(struct iovec));
-            lock_iovec(vec, arg2, count, 1);
+            if( copy_from_iovec(vec, arg2, count, 1) ) return -EFAULT;
             ret = get_errno(writev(arg1, vec, count));
-            unlock_iovec(vec, arg2, count, 0);
+            if( copy_to_iovec(vec, arg2, count, 0) )  return -EFAULT;
         }
         break;
     case TARGET_NR_getsid: