ipc: separate msg allocation from userspace copy

Separating msg allocation enables single-block vmalloc
allocation instead.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 38 insertions, 14 deletions

diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index 98b1c2b476cc..0a5c8a95c257 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -44,21 +44,54 @@ struct msg_msgseg {
 #define DATALEN_MSG     (int)(PAGE_SIZE-sizeof(struct msg_msg))
 #define DATALEN_SEG     (int)(PAGE_SIZE-sizeof(struct msg_msgseg))
 
-struct msg_msg *load_msg(const void __user *src, int len)
+
+static struct msg_msg *alloc_msg(int len)
 {
         struct msg_msg *msg;
         struct msg_msgseg **pseg;
-        int err;
         int alen;
 
         alen = min(len, DATALEN_MSG);
         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
         if (msg == NULL)
-                return ERR_PTR(-ENOMEM);
+                return NULL;
 
         msg->next = NULL;
         msg->security = NULL;
 
+        len -= alen;
+        pseg = &msg->next;
+        while (len > 0) {
+                struct msg_msgseg *seg;
+                alen = min(len, DATALEN_SEG);
+                seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
+                if (seg == NULL)
+                        goto out_err;
+                *pseg = seg;
+                seg->next = NULL;
+                pseg = &seg->next;
+                len -= alen;
+        }
+
+        return msg;
+
+out_err:
+        free_msg(msg);
+        return NULL;
+}
+
+struct msg_msg *load_msg(const void __user *src, int len)
+{
+        struct msg_msg *msg;
+        struct msg_msgseg *seg;
+        int err;
+        int alen;
+
+        msg = alloc_msg(len);
+        if (msg == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        alen = min(len, DATALEN_MSG);
         if (copy_from_user(msg + 1, src, alen)) {
                 err = -EFAULT;
                 goto out_err;
@@ -66,23 +99,14 @@ struct msg_msg *load_msg(const void __user *src, int len)
 
         len -= alen;
         src = ((char __user *)src) + alen;
-        pseg = &msg->next;
+        seg = msg->next;
         while (len > 0) {
-                struct msg_msgseg *seg;
                 alen = min(len, DATALEN_SEG);
-                seg = kmalloc(sizeof(*seg) + alen,
-                                                 GFP_KERNEL);
-                if (seg == NULL) {
-                        err = -ENOMEM;
-                        goto out_err;
-                }
-                *pseg = seg;
-                seg->next = NULL;
                 if (copy_from_user(seg + 1, src, alen)) {
                         err = -EFAULT;
                         goto out_err;
                 }
-                pseg = &seg->next;
+                seg = seg->next;
                 len -= alen;
                 src = ((char __user *)src) + alen;
         }