[patch 74/83] uml: boot broken due to buffer overrun

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

commit 361371201b60ffd686a694c848c1d5ad6061725f upstream.

mconsole_init() passed 256 bytes as length in os_create_unix_socket, while
the sizeof UNIX_PATH_MAX is 108. This patch fixes that problem and avoids
a big overrun bug reported on UML bootup.

sockaddr_un.sun_path is UNIX_PATH_MAX long which causes the problem.
Reported-by: Vikas K Managutte <vikki.km@xxxxxxxxx>
Reported-by: Sarvesh Kumar Lal Das <skldas@xxxxxxxxx>
Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Reviewed-by: WANG Cong <wangcong@xxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/um/drivers/mconsole_kern.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -16,6 +16,8 @@
 #include <linux/slab.h>
 #include <linux/syscalls.h>
 #include <linux/utsname.h>
+#include <linux/socket.h>
+#include <linux/un.h>
 #include <linux/workqueue.h>
 #include <linux/mutex.h>
 #include <asm/uaccess.h>
@@ -785,7 +787,7 @@ static int __init mconsole_init(void)
 	/* long to avoid size mismatch warnings from gcc */
 	long sock;
 	int err;
-	char file[256];
+	char file[UNIX_PATH_MAX];
 
 	if (umid_file_name("mconsole", file, sizeof(file)))
 		return -1;

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