Buffer overrun in arch/x86_64/sys_ia32.c:sys32_ni_syscall()

[Jeremy Fitzhardinge <jeremy@goop.org>]

struct task_struct.comm is defined to be 16 chars, but
arch/x86_64/sys_ia32.c:sys32_ni_syscall() copies it into a static 8 byte
buffer, which will surely cause problems.  This patch makes lastcomm[]
the right size, and makes sure it can't be overrun.  Since the code also
goes to the effort of getting a local copy of current in "me", we may as
well use it for printing the message.

Patch is against 2.6.10-rc2-mm3.

	J

 arch/x86_64/ia32/sys_ia32.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff -puN arch/x86_64/ia32/sys_ia32.c~short-comm-string arch/x86_64/ia32/sys_ia32.c
--- local-2.6/arch/x86_64/ia32/sys_ia32.c~short-comm-string	2004-11-29 19:51:02.922621617 -0800
+++ local-2.6-jeremy/arch/x86_64/ia32/sys_ia32.c	2004-11-29 19:52:43.493561830 -0800
@@ -525,11 +525,12 @@ sys32_waitpid(compat_pid_t pid, unsigned
 int sys32_ni_syscall(int call)
 { 
 	struct task_struct *me = current;
-	static char lastcomm[8];
-	if (strcmp(lastcomm, me->comm)) {
-	printk(KERN_INFO "IA32 syscall %d from %s not implemented\n", call,
-	       current->comm);
-		strcpy(lastcomm, me->comm); 
+	static char lastcomm[sizeof(me->comm)];
+
+	if (strncmp(lastcomm, me->comm, sizeof(lastcomm))) {
+		printk(KERN_INFO "IA32 syscall %d from %s not implemented\n", call,
+		       me->comm);
+		strncpy(lastcomm, me->comm, sizeof(lastcomm));
 	} 
 	return -ENOSYS;	       
 } 

_