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authorsuzuki <suzuki@linux.vnet.ibm.com>2006-12-06 20:37:48 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:38 -0800
commit651971cb7242e8f6d7ebd153e69bd271cb731223 (patch)
tree38c8bd3c461cb09a538664ddc78e5452fdf28f29 /include/linux
parent19e5d9c0d2194b4b47189cbec2921cbf72b0bd1c (diff)
[PATCH] Fix the size limit of compat space msgsize
Currently we allocate 64k space on the user stack and use it the msgbuf for sys_{msgrcv,msgsnd} for compat and the results are later copied in user [ by copy_in_user]. This patch introduces helper routines for sys_{msgrcv,msgsnd} as below: do_msgsnd() : Accepts the mtype and user space ptr to the buffer along with the msqid and msgflg. do_msgrcv() : Accepts a kernel space ptr to mtype and a userspace ptr to the buffer. The mtype has to be copied back the user space msgbuf by the caller. These changes avoid the need to allocate the msgsize on the userspace ( thus removing the size limt ) and the overhead of an extra copy_in_user(). Signed-off-by: Suzuki K P <suzuki@in.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/msg.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/msg.h b/include/linux/msg.h
index acc7c174ff0..f1b60740d64 100644
--- a/include/linux/msg.h
+++ b/include/linux/msg.h
@@ -92,6 +92,12 @@ struct msg_queue {
struct list_head q_senders;
};
+/* Helper routines for sys_msgsnd and sys_msgrcv */
+extern long do_msgsnd(int msqid, long mtype, void __user *mtext,
+ size_t msgsz, int msgflg);
+extern long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
+ size_t msgsz, long msgtyp, int msgflg);
+
#endif /* __KERNEL__ */
#endif /* _LINUX_MSG_H */