[Qemu-devel] [PATCH] linux-user/syscall.c: Fix issue for checking ptr in different address spaces in TARGET_CMSG_NXTHDR

[gang.chen.5i5j@gmail.com]

From: Chen Gang <gang.chen.5i5j@gmail.com>

After fix this issue, qemu can run i386 wine notepad.exe successfully.
But the initialization performance is not quite well.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 linux-user/syscall.c      | 30 +++++++++++++++++-------------
 linux-user/syscall_defs.h | 20 +++++++++-----------
 2 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 973cc2f..521749c 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1181,17 +1181,18 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
     struct cmsghdr *cmsg = CMSG_FIRSTHDR(msgh);
     abi_long msg_controllen;
     abi_ulong target_cmsg_addr;
-    struct target_cmsghdr *target_cmsg;
+    struct target_cmsghdr *target_cmsg, *base;
     socklen_t space = 0;
     
     msg_controllen = tswapal(target_msgh->msg_controllen);
     if (msg_controllen < sizeof (struct target_cmsghdr)) 
         goto the_end;
     target_cmsg_addr = tswapal(target_msgh->msg_control);
-    target_cmsg = lock_user(VERIFY_READ, target_cmsg_addr, msg_controllen, 1);
-    if (!target_cmsg)
+    base = lock_user(VERIFY_READ, target_cmsg_addr, msg_controllen, 1);
+    if (!base) {
         return -TARGET_EFAULT;
-
+    }
+    target_cmsg = base;
     while (cmsg && target_cmsg) {
         void *data = CMSG_DATA(cmsg);
         void *target_data = TARGET_CMSG_DATA(target_cmsg);
@@ -1247,7 +1248,7 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
         }
 
         cmsg = CMSG_NXTHDR(msgh, cmsg);
-        target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg);
+        target_cmsg = TARGET_CMSG_NXTHDR(base, msg_controllen, target_cmsg);
     }
     unlock_user(target_cmsg, target_cmsg_addr, 0);
  the_end:
@@ -1259,19 +1260,22 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
                                            struct msghdr *msgh)
 {
     struct cmsghdr *cmsg = CMSG_FIRSTHDR(msgh);
-    abi_long msg_controllen;
+    abi_long msg_controllen, size;
     abi_ulong target_cmsg_addr;
-    struct target_cmsghdr *target_cmsg;
+    struct target_cmsghdr *target_cmsg, *base;
     socklen_t space = 0;
 
-    msg_controllen = tswapal(target_msgh->msg_controllen);
-    if (msg_controllen < sizeof (struct target_cmsghdr)) 
+    size = tswapal(target_msgh->msg_controllen);
+    if (size < sizeof(struct target_cmsghdr)) {
         goto the_end;
+    }
     target_cmsg_addr = tswapal(target_msgh->msg_control);
-    target_cmsg = lock_user(VERIFY_WRITE, target_cmsg_addr, msg_controllen, 0);
-    if (!target_cmsg)
+    base = lock_user(VERIFY_WRITE, target_cmsg_addr, size, 0);
+    if (!base) {
         return -TARGET_EFAULT;
-
+    }
+    msg_controllen = size;
+    target_cmsg = base;
     while (cmsg && target_cmsg) {
         void *data = CMSG_DATA(cmsg);
         void *target_data = TARGET_CMSG_DATA(target_cmsg);
@@ -1389,7 +1393,7 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
         msg_controllen -= tgt_space;
         space += tgt_space;
         cmsg = CMSG_NXTHDR(msgh, cmsg);
-        target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg);
+        target_cmsg = TARGET_CMSG_NXTHDR(base, size, target_cmsg);
     }
     unlock_user(target_cmsg, target_cmsg_addr, space);
  the_end:
diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
index 5256fe5..aec2f23 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -234,7 +234,8 @@ struct target_cmsghdr {
 };
 
 #define TARGET_CMSG_DATA(cmsg) ((unsigned char *) ((struct target_cmsghdr *) (cmsg) + 1))
-#define TARGET_CMSG_NXTHDR(mhdr, cmsg) __target_cmsg_nxthdr (mhdr, cmsg)
+#define TARGET_CMSG_NXTHDR(base, size, cmsg) __target_cmsg_nxthdr(base, size, \
+                                                                  cmsg)
 #define TARGET_CMSG_ALIGN(len) (((len) + sizeof (abi_long) - 1) \
                                & (size_t) ~(sizeof (abi_long) - 1))
 #define TARGET_CMSG_SPACE(len) (TARGET_CMSG_ALIGN (len) \
@@ -242,17 +243,14 @@ struct target_cmsghdr {
 #define TARGET_CMSG_LEN(len)   (TARGET_CMSG_ALIGN (sizeof (struct target_cmsghdr)) + (len))
 
 static __inline__ struct target_cmsghdr *
-__target_cmsg_nxthdr (struct target_msghdr *__mhdr, struct target_cmsghdr *__cmsg)
+__target_cmsg_nxthdr(void *base, abi_long size, struct target_cmsghdr *msg)
 {
-  struct target_cmsghdr *__ptr;
-
-  __ptr = (struct target_cmsghdr *)((unsigned char *) __cmsg
-                                    + TARGET_CMSG_ALIGN (tswapal(__cmsg->cmsg_len)));
-  if ((unsigned long)((char *)(__ptr+1) - (char *)(size_t)tswapal(__mhdr->msg_control))
-      > tswapal(__mhdr->msg_controllen))
-    /* No more entries.  */
-    return (struct target_cmsghdr *)0;
-  return __cmsg;
+    msg = (struct target_cmsghdr *)((unsigned char *)msg +
+                                    TARGET_CMSG_ALIGN(tswapal(msg->cmsg_len)));
+    if ((unsigned long)((char *)(msg + 1) - (char *)base) > size) {
+        return NULL;
+    }
+    return msg;
 }
 
 struct target_mmsghdr {
-- 
1.9.1