linux-kernel - Re: [PATCH v3] kernel/signal.c: fix BUG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 26 Jun 2013 18:59:00 +0200
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	James Hogan <james.hogan@...tec.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Daney <ddaney@...iumnetworks.com>,
	David Daney <ddaney.cavm@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Kees Cook <keescook@...omium.org>,
	David Daney <david.daney@...ium.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	David Howells <dhowells@...hat.com>,
	Dave Jones <davej@...hat.com>, linux-mips@...ux-mips.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v3] kernel/signal.c: fix BUG_ON with SIG128 (MIPS)

On Wed, Jun 26, 2013 at 06:14:52PM +0200, Oleg Nesterov wrote:

> Or simply remove the BUG_ON(), this can equally confuse wait(status).
> 128 & 0x7f == 0.
> 
> Still I think it would be better to change _NSIG on mips.

If it was that easy.  That's going to outright break binary compatibility,
see kernel/signal.c:

SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
                sigset_t __user *, oset, size_t, sigsetsize)
{
        sigset_t old_set, new_set;
        int error;

        /* XXX: Don't preclude handling different sized sigset_t's.  */
        if (sigsetsize != sizeof(sigset_t))
                return -EINVAL;

There are several more more syscalls performing tests like the above.

So at least the kernel sigset_t will have to remain constant, maybe something
like below, totally untested patch which I'm sure is going to open a few
20 foot containers full of worms such as NSIG being defined by glibc to 128
and fixing the kernel won't magically change installed libc headers or
binaries incorporating NSIG.

  Ralf

 arch/mips/include/uapi/asm/signal.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/uapi/asm/signal.h b/arch/mips/include/uapi/asm/signal.h
index addb9f5..8bba323 100644
--- a/arch/mips/include/uapi/asm/signal.h
+++ b/arch/mips/include/uapi/asm/signal.h
@@ -11,12 +11,13 @@
 
 #include <linux/types.h>
 
-#define _NSIG		128
+#define _NSIG		64
 #define _NSIG_BPW	(sizeof(unsigned long) * 8)
 #define _NSIG_WORDS	(_NSIG / _NSIG_BPW)
 
 typedef struct {
 	unsigned long sig[_NSIG_WORDS];
+	unsigned long __fill[_NSIG_WORDS];
 } sigset_t;
 
 typedef unsigned long old_sigset_t;		/* at least 32 bits */
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/