linux-stable.git/arch/alpha/kernel/osf_sys.c, branch v3.2.98

osf_wait4(): fix infoleak

2017-09-15T17:30:46+00:00

commit a8c39544a6eb2093c04afd5005b6192bd0e880c6 upstream.

failing sys_wait4() won't fill struct rusage...

Signed-off-by: Al Viro 
Signed-off-by: Ben Hutchings

mm: larger stack guard gap, between vmas

2017-07-02T16:12:47+00:00

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.

Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov 
Original-patch-by: Michal Hocko 
Signed-off-by: Hugh Dickins 
Acked-by: Michal Hocko 
Tested-by: Helge Deller  # parisc
Signed-off-by: Linus Torvalds 
[Hugh Dickins: Backported to 3.2]
[bwh: Fix more instances of vma->vm_start in sparc64 impl. of
 arch_get_unmapped_area_topdown() and generic impl. of
 hugetlb_get_unmapped_area()]
Signed-off-by: Ben Hutchings

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

2011-08-25T23:25:33+00:00

The bug was accidentally found by the following program:

    #include 
    #include 
    #include 
    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 745dd2405e28
"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 
Acked-by: Michael Cree 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

alpha: fix several security issues

2011-06-16T03:04:02+00:00

Fix several security issues in Alpha-specific syscalls.  Untested, but
mostly trivial.

1. Signedness issue in osf_getdomainname allows copying out-of-bounds
kernel memory to userland.

2. Signedness issue in osf_sysinfo allows copying large amounts of
kernel memory to userland.

3. Typo (?) in osf_getsysinfo bounds minimum instead of maximum copy
size, allowing copying large amounts of kernel memory to userland.

4. Usage of user pointer in osf_wait4 while under KERNEL_DS allows
privilege escalation via writing return value of sys_wait4 to kernel
memory.

Signed-off-by: Dan Rosenberg 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

clean statfs-like syscalls up

2011-03-14T13:15:28+00:00

New helpers: user_statfs() and fd_statfs(), taking userland pathname and
descriptor resp. and filling struct kstatfs.  Syscalls of statfs family
(native, compat and foreign - osf and hpux on alpha and parisc resp.)
switched to those.  Removes some boilerplate code, simplifies cleanup
on errors...

Signed-off-by: Al Viro

alpha/osf_sys: remove unused MAX_SELECT_SECONDS

2011-01-17T04:42:14+00:00

Remove the leftover from the commit 14e2acd86865 ("select:
fix alpha OSF wrapper").

Signed-off-by: Namhyung Kim 
Cc: Arjan van de Ven 
Signed-off-by: Matt Turner

alpha: kill big kernel lock

2010-09-19T03:06:18+00:00

All uses of the BKL on alpha are totally bogus, nothing
is really protected by this. Remove the remaining users
so we don't have to mark alpha as 'depends on BKL'.

Signed-off-by: Arnd Bergmann 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Matt Turner

alpha: Use static const char * const where possible

2010-09-19T03:06:17+00:00

Acked-by: Richard Henderson  
Signed-off-by: Joe Perches 
Signed-off-by: Matt Turner

Alpha: Fix a missing comma in sys_osf_statfs()

2010-08-28T21:01:03+00:00

Fix a comma that got accidentally deleted from sys_osf_statfs() leading to the
following warning:

  arch/alpha/kernel/osf_sys.c: In function 'SYSC_osf_statfs':
  arch/alpha/kernel/osf_sys.c:255: error: syntax error before 'buffer'

Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

Mark arguments to certain syscalls as being const

2010-08-13T23:53:13+00:00

Mark arguments to certain system calls as being const where they should be but
aren't.  The list includes:

 (*) The filename arguments of various stat syscalls, execve(), various utimes
     syscalls and some mount syscalls.

 (*) The filename arguments of some syscall helpers relating to the above.

 (*) The buffer argument of various write syscalls.

Signed-off-by: David Howells 
Acked-by: David S. Miller 
Signed-off-by: Linus Torvalds