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Subject[ 105/109] m68k: Make sys_atomic_cmpxchg_32 work on classic m68k
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Andreas Schwab <schwab@linux-m68k.org>

commit 9e2760d18b3cf179534bbc27692c84879c61b97c upstream.

User space access must always go through uaccess accessors, since on
classic m68k user space and kernel space are completely separate.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Tested-by: Thorsten Glaser <tg@debian.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/m68k/kernel/sys_m68k.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/m68k/kernel/sys_m68k.c
+++ b/arch/m68k/kernel/sys_m68k.c
@@ -479,9 +479,13 @@ sys_atomic_cmpxchg_32(unsigned long newv
goto bad_access;
}

- mem_value = *mem;
+ /*
+ * No need to check for EFAULT; we know that the page is
+ * present and writable.
+ */
+ __get_user(mem_value, mem);
if (mem_value == oldval)
- *mem = newval;
+ __put_user(newval, mem);

pte_unmap_unlock(pte, ptl);
up_read(&mm->mmap_sem);



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