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

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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 745dd2405e
"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Deleted outdated out-of-sync 'UAC_SHIFT' (the cause of bug) in favour of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: Sergei Trofimovich <slyfox@gentoo.org>
Acked-by: Michael 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sergei Trofimovich 2011-08-25 15:59:02 -07:00 committed by Linus Torvalds
parent 06ed4625fd
commit 2df7a7d1cd
3 changed files with 11 additions and 18 deletions
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9
arch/alpha/include/asm/sysinfo.h
View file

@ -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 */

8
arch/alpha/include/asm/thread_info.h
View file

@ -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)

12
arch/alpha/kernel/osf_sys.c
View file

@ -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>
@ -633,9 +634,10 @@ 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;
if (put_user(w, (unsigned int __user *)buffer))
return -EFAULT;
w = (current_thread_info()->flags >> ALPHA_UAC_SHIFT) &
UAC_BITMASK;
if (put_user(w, (unsigned int __user *)buffer))
return -EFAULT;
return 1;
case GSI_PROC_TYPE:
@ -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;