linux-stable.git/arch/alpha, branch v3.16.67

alpha: fix page fault handling for r16-r18 targets

2019-05-02T20:41:51+00:00

commit 491af60ffb848b59e82f7c9145833222e0bf27a5 upstream.

Fix page fault handling code to fixup r16-r18 registers.
Before the patch code had off-by-two registers bug.
This bug caused overwriting of ps,pc,gp registers instead
of fixing intended r16,r17,r18 (see `struct pt_regs`).

More details:

Initially Dmitry noticed a kernel bug as a failure
on strace test suite. Test passes unmapped userspace
pointer to io_submit:

```c
    #include 
    #include 
    #include 
    #include 
    int main(void)
    {
        unsigned long ctx = 0;
        if (syscall(__NR_io_setup, 1, &ctx))
            err(1, "io_setup");
        const size_t page_size = sysconf(_SC_PAGESIZE);
        const size_t size = page_size * 2;
        void *ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
                         MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
        if (MAP_FAILED == ptr)
            err(1, "mmap(%zu)", size);
        if (munmap(ptr, size))
            err(1, "munmap");
        syscall(__NR_io_submit, ctx, 1, ptr + page_size);
        syscall(__NR_io_destroy, ctx);
        return 0;
    }
```

Running this test causes kernel to crash when handling page fault:

```
    Unable to handle kernel paging request at virtual address ffffffffffff9468
    CPU 3
    aio(26027): Oops 0
    pc = []  ra = []  ps = 0000    Not tainted
    pc is at sys_io_submit+0x108/0x200
    ra is at sys_io_submit+0x6c/0x200
    v0 = fffffc00c58e6300  t0 = fffffffffffffff2  t1 = 000002000025e000
    t2 = fffffc01f159fef8  t3 = fffffc0001009640  t4 = fffffc0000e0f6e0
    t5 = 0000020001002e9e  t6 = 4c41564e49452031  t7 = fffffc01f159c000
    s0 = 0000000000000002  s1 = 000002000025e000  s2 = 0000000000000000
    s3 = 0000000000000000  s4 = 0000000000000000  s5 = fffffffffffffff2
    s6 = fffffc00c58e6300
    a0 = fffffc00c58e6300  a1 = 0000000000000000  a2 = 000002000025e000
    a3 = 00000200001ac260  a4 = 00000200001ac1e8  a5 = 0000000000000001
    t8 = 0000000000000008  t9 = 000000011f8bce30  t10= 00000200001ac440
    t11= 0000000000000000  pv = fffffc00006fd320  at = 0000000000000000
    gp = 0000000000000000  sp = 00000000265fd174
    Disabling lock debugging due to kernel taint
    Trace:
    [] entSys+0xa4/0xc0
```

Here `gp` has invalid value. `gp is s overwritten by a fixup for the
following page fault handler in `io_submit` syscall handler:

```
    __se_sys_io_submit
    ...
        ldq     a1,0(t1)
        bne     t0,4280 <__se_sys_io_submit+0x180>
```

After a page fault `t0` should contain -EFALUT and `a1` is 0.
Instead `gp` was overwritten in place of `a1`.

This happens due to a off-by-two bug in `dpf_reg()` for `r16-r18`
(aka `a0-a2`).

I think the bug went unnoticed for a long time as `gp` is one
of scratch registers. Any kernel function call would re-calculate `gp`.

Dmitry tracked down the bug origin back to 2.1.32 kernel version
where trap_a{0,1,2} fields were inserted into struct pt_regs.
And even before that `dpf_reg()` contained off-by-one error.

Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: linux-alpha@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reported-and-reviewed-by: "Dmitry V. Levin" 
Bug: https://bugs.gentoo.org/672040
Signed-off-by: Sergei Trofimovich 
Signed-off-by: Matt Turner 
Signed-off-by: Ben Hutchings

arch/alpha, termios: implement BOTHER, IBSHIFT and termios2

2019-02-11T17:53:54+00:00

commit d0ffb805b729322626639336986bc83fc2e60871 upstream.

Alpha has had c_ispeed and c_ospeed, but still set speeds in c_cflags
using arbitrary flags. Because BOTHER is not defined, the general
Linux code doesn't allow setting arbitrary baud rates, and because
CBAUDEX == 0, we can have an array overrun of the baud_rate[] table in
drivers/tty/tty_baudrate.c if (c_cflags & CBAUD) == 037.

Resolve both problems by #defining BOTHER to 037 on Alpha.

However, userspace still needs to know if setting BOTHER is actually
safe given legacy kernels (does anyone actually care about that on
Alpha anymore?), so enable the TCGETS2/TCSETS*2 ioctls on Alpha, even
though they use the same structure. Define struct termios2 just for
compatibility; it is the exact same structure as struct termios. In a
future patchset, this will be cleaned up so the uapi headers are
usable from libc.

Signed-off-by: H. Peter Anvin (Intel) 
Cc: Jiri Slaby 
Cc: Al Viro 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Thomas Gleixner 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Eugene Syromiatnikov 
Cc: 
Cc: 
Cc: Johan Hovold 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

alpha: drop _PAGE_FILE and pte_file()-related helpers

2018-10-03T03:09:52+00:00

commit b816157a5366550c5ee29a6431ba1abb88721266 upstream.

We've replaced remap_file_pages(2) implementation with emulation.  Nobody
creates non-linear mapping anymore.

Signed-off-by: Kirill A. Shutemov 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

alpha: fix crash if pthread_create races with signal delivery

2018-06-16T21:21:56+00:00

commit 21ffceda1c8b3807615c40d440d7815e0c85d366 upstream.

On alpha, a process will crash if it attempts to start a thread and a
signal is delivered at the same time. The crash can be reproduced with
this program: https://cygwin.com/ml/cygwin/2014-11/msg00473.html

The reason for the crash is this:
* we call the clone syscall
* we go to the function copy_process
* copy process calls copy_thread_tls, it is a wrapper around copy_thread
* copy_thread sets the tls pointer: childti->pcb.unique = regs->r20
* copy_thread sets regs->r20 to zero
* we go back to copy_process
* copy process checks "if (signal_pending(current))" and returns
  -ERESTARTNOINTR
* the clone syscall is restarted, but this time, regs->r20 is zero, so
  the new thread is created with zero tls pointer
* the new thread crashes in start_thread when attempting to access tls

The comment in the code says that setting the register r20 is some
compatibility with OSF/1. But OSF/1 doesn't use the CLONE_SETTLS flag, so
we don't have to zero r20 if CLONE_SETTLS is set. This patch fixes the bug
by zeroing regs->r20 only if CLONE_SETTLS is not set.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Matt Turner 
Signed-off-by: Ben Hutchings

alpha: fix reboot on Avanti platform

2018-06-16T21:21:56+00:00

commit 55fc633c41a08ce9244ff5f528f420b16b1e04d6 upstream.

We need to define NEED_SRM_SAVE_RESTORE on the Avanti, otherwise we get
machine check exception when attempting to reboot the machine.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Matt Turner 
Signed-off-by: Ben Hutchings

ptrace: Don't allow accessing an undumpable mm

2018-01-01T20:52:11+00:00

commit 84d77d3f06e7e8dea057d10e8ec77ad71f721be3 upstream.

It is the reasonable expectation that if an executable file is not
readable there will be no way for a user without special privileges to
read the file.  This is enforced in ptrace_attach but if ptrace
is already attached before exec there is no enforcement for read-only
executables.

As the only way to read such an mm is through access_process_vm
spin a variant called ptrace_access_vm that will fail if the
target process is not being ptraced by the current process, or
the current process did not have sufficient privileges when ptracing
began to read the target processes mm.

In the ptrace implementations replace access_process_vm by
ptrace_access_vm.  There remain several ptrace sites that still use
access_process_vm as they are reading the target executables
instructions (for kernel consumption) or register stacks.  As such it
does not appear necessary to add a permission check to those calls.

This bug has always existed in Linux.

Fixes: v1.0
Reported-by: Andy Lutomirski 
Signed-off-by: "Eric W. Biederman" 
[bwh: Backported to 3.16:
 - Pass around only a write flag, not gup_flags
 - Adjust context]
Signed-off-by: Ben Hutchings

alpha: uapi: Add support for __SANE_USERSPACE_TYPES__

2017-11-11T13:33:33+00:00

commit cec80d82142ab25c71eee24b529cfeaf17c43062 upstream.

This fixes compiler errors in perf such as:

tests/attr.c: In function 'store_event':
tests/attr.c:66:27: error: format '%llu' expects argument of type 'long long unsigned int', but argument 6 has type '__u64 {aka long unsigned int}' [-Werror=format=]
  snprintf(path, PATH_MAX, "%s/event-%d-%llu-%d", dir,
                           ^

Signed-off-by: Ben Hutchings 
Tested-by: Michael Cree 
Signed-off-by: Matt Turner

osf_wait4(): fix infoleak

2017-09-15T17:29:47+00:00

commit a8c39544a6eb2093c04afd5005b6192bd0e880c6 upstream.

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

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

alpha: fix copy_from_user()

2016-11-20T01:17:25+00:00

commit 2561d309dfd1555e781484af757ed0115035ddb3 upstream.

it should clear the destination even when access_ok() fails.

Signed-off-by: Al Viro 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

alpha/PCI: Call iomem_is_exclusive() for IORESOURCE_MEM, but not IORESOURCE_IO

2016-08-22T21:37:51+00:00

commit c20e128030caf0537d5e906753eac1c28fefdb75 upstream.

The alpha pci_mmap_resource() is used for both IORESOURCE_MEM and
IORESOURCE_IO resources, but iomem_is_exclusive() is only applicable for
IORESOURCE_MEM.

Call iomem_is_exclusive() only for IORESOURCE_MEM resources, and do it
earlier to match the generic version of pci_mmap_resource().

Fixes: 10a0ef39fbd1 ("PCI/alpha: pci sysfs resources")
Signed-off-by: Bjorn Helgaas 
CC: Ivan Kokshaysky 
Signed-off-by: Ben Hutchings