mm/memory.c: check return value of ioremap_prot

ioremap_prot() can return NULL which could lead to an oops.

Link: http://lkml.kernel.org/r/1533195441-58594-1-git-send-email-chenjie6@huawei.com
Signed-off-by: chen jie <chenjie6@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: chenjie <chenjie6@huawei.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index dab1511294ad..c5e87a3a82ba 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4395,6 +4395,9 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
                 return -EINVAL;
 
         maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
+        if (!maddr)
+                return -ENOMEM;
+
         if (write)
                 memcpy_toio(maddr + offset, buf, len);
         else