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Commit 2df7a7d1 authored by Sergei Trofimovich's avatar Sergei Trofimovich Committed by Linus Torvalds
Browse files

alpha: unbreak osf_setsysinfo(SSI_NVPAIRS, [SSIN_UACPROC, UAC_SIGBUS]) 



The bug was accidentally found by the following program:

    #include <asm/sysinfo.h>
    #include <asm/unistd.h>
    #include <sys/syscall.h>
    static int setsysinfo(unsigned long op, void *buffer, unsigned long size,
                          int *start, void *arg, unsigned long flag) {
        return syscall(__NR_osf_setsysinfo, op, buffer, size, start, arg, flag);
    }

    int main(int argc, char **argv) {
        short x[10];
        unsigned int buf[2] = { SSIN_UACPROC, UAC_SIGBUS, };
        setsysinfo(SSI_NVPAIRS, buf, 1, 0, 0, 0);

        int  *y = (int*) (x+1);
        *y = 0;
        return 0;
    }

The program shoud fail on SIGBUS, but didn't.

The patch is a second part of userspace flag fix (commit 745dd240
"Alpha: Rearrange thread info flags fixing two regressions").

Deleted outdated out-of-sync 'UAC_SHIFT' (the cause of bug) in favour of
'ALPHA_UAC_SHIFT'.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarSergei Trofimovich <slyfox@gentoo.org>
Acked-by: default avatarMichael Cree <mcree@orcon.net.nz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 06ed4625

arch/alpha/include/asm/sysinfo.h

+0 −9
Original line number Diff line number Diff line
@@ -27,13 +27,4 @@ 
#define UAC_NOFIX			2

#define UAC_SIGBUS			4





#ifdef __KERNEL__



/* This is the shift that is applied to the UAC bits as stored in the

   per-thread flags.  See thread_info.h.  */

#define UAC_SHIFT			6



#endif



#endif /* __ASM_ALPHA_SYSINFO_H */

arch/alpha/include/asm/thread_info.h

+4 −4
Original line number Diff line number Diff line
@@ -74,9 +74,9 @@ register struct thread_info *__current_thread_info __asm__("$8"); 
#define TIF_NEED_RESCHED	3	/* rescheduling necessary */

#define TIF_POLLING_NRFLAG	8	/* poll_idle is polling NEED_RESCHED */

#define TIF_DIE_IF_KERNEL	9	/* dik recursion lock */

#define TIF_UAC_NOPRINT		10	/* see sysinfo.h */

#define TIF_UAC_NOFIX		11

#define TIF_UAC_SIGBUS		12

#define TIF_UAC_NOPRINT		10	/* ! Preserve sequence of following */

#define TIF_UAC_NOFIX		11	/* ! flags as they match            */

#define TIF_UAC_SIGBUS		12	/* ! userspace part of 'osf_sysinfo' */

#define TIF_MEMDIE		13	/* is terminating due to OOM killer */

#define TIF_RESTORE_SIGMASK	14	/* restore signal mask in do_signal */

#define TIF_FREEZE		16	/* is freezing for suspend */
@@ -97,7 +97,7 @@ register struct thread_info *__current_thread_info __asm__("$8"); 
#define _TIF_ALLWORK_MASK	(_TIF_WORK_MASK		\

				 | _TIF_SYSCALL_TRACE)



#define ALPHA_UAC_SHIFT		10

#define ALPHA_UAC_SHIFT		TIF_UAC_NOPRINT

#define ALPHA_UAC_MASK		(1 << TIF_UAC_NOPRINT | 1 << TIF_UAC_NOFIX | \

				 1 << TIF_UAC_SIGBUS)

arch/alpha/kernel/osf_sys.c

+7 −5
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 
#include <asm/uaccess.h>

#include <asm/system.h>

#include <asm/sysinfo.h>

#include <asm/thread_info.h>

#include <asm/hwrpb.h>

#include <asm/processor.h>
@@ -633,7 +634,8 @@ SYSCALL_DEFINE5(osf_getsysinfo, unsigned long, op, void __user *, buffer, 
 	case GSI_UACPROC:

		if (nbytes < sizeof(unsigned int))

			return -EINVAL;

 		w = (current_thread_info()->flags >> UAC_SHIFT) & UAC_BITMASK;

		w = (current_thread_info()->flags >> ALPHA_UAC_SHIFT) &

			UAC_BITMASK;

		if (put_user(w, (unsigned int __user *)buffer))

			return -EFAULT;

 		return 1;
@@ -756,8 +758,8 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer, 
 			case SSIN_UACPROC:

			again:

				old = current_thread_info()->flags;

				new = old & ~(UAC_BITMASK << UAC_SHIFT);

				new = new | (w & UAC_BITMASK) << UAC_SHIFT;

				new = old & ~(UAC_BITMASK << ALPHA_UAC_SHIFT);

				new = new | (w & UAC_BITMASK) << ALPHA_UAC_SHIFT;

				if (cmpxchg(&current_thread_info()->flags,

					    old, new) != old)

					goto again;