Problem with recent CMSG_COMPAT_OK fix

Hi,

The recent fixes for cmsg_len handling seem to break 32bit compatibility at least on x86_64. The new CMSG_COMPAT_OK macro requires that cmsg_len is greater or equal the size of struct cmsghdr, which is the 64bit version of the struct. The code should really check against the size of struct compat_cmsghdr.

@@ -125,7 +125,7 @@
 	 (struct compat_cmsghdr __user *)NULL)
 
 #define CMSG_COMPAT_OK(ucmlen, ucmsg, mhdr) \
-	((ucmlen) >= sizeof(struct cmsghdr) && \
+	((ucmlen) >= sizeof(struct compat_cmsghdr) && \
 	 (ucmlen) <= (unsigned long) \
 	 ((mhdr)->msg_controllen - \
 	  ((char *)(ucmsg) - (char *)(mhdr)->msg_control)))

Olaf Kirch     | Things that make Monday morning interesting, #2:
[email protected]   |        "We have 8,000 NFS mount points, why do we keep
---------------+ 	 running out of privileged ports?"

From: Olaf Kirch <[email protected]>
Subject: Fix cmsg_len checks in 32bit compat mode
References: 49517 - LTC13227

The recent fixes for cmsg_len handling seem to break 32bit compatibility at least on x86_64. The new CMSG_COMPAT_OK macro requires that cmsg_len is greater or equal the size of struct cmsghdr, which is the 64bit version of the struct. The code should really check against the size of struct compat_cmsghdr.

@@ -125,7 +125,7 @@
 	 (struct compat_cmsghdr __user *)NULL)
 
 #define CMSG_COMPAT_OK(ucmlen, ucmsg, mhdr) \
-	((ucmlen) >= sizeof(struct cmsghdr) && \
+	((ucmlen) >= sizeof(struct compat_cmsghdr) && \
 	 (ucmlen) <= (unsigned long) \
 	 ((mhdr)->msg_controllen - \
 	  ((char *)(ucmsg) - (char *)(mhdr)->msg_control)))

Applied, thanks Olaf.