mm: actually remap enough memory

For whatever reason, generic_access_phys() only remaps one page, but
actually allows to access arbitrary size. It's quite easy to trigger
large reads, like printing out large structure with gdb, which leads to
a crash. Fix it by remapping correct size.

Fixes: 28b2ee20c7cb ("access_process_vm device memory infrastructure")
Cc: stable@vger.kernel.org
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>

diff --git a/mm/memory.c b/mm/memory.c
index b9a95f1..79c71de 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3836,7 +3836,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
        if (follow_phys(vma, addr, write, &prot, &phys_addr))
                return -EINVAL;
 
-       maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
+       maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
        if (write)
                memcpy_toio(maddr + offset, buf, len);
        else