ia64/err-inject: Use get_user_pages_fast()

[ Upstream commit 69c907022a7d9325cdc5c9dd064571e445df9a47 ]

At the point of sysfs callback, the call to gup is
done without mmap_sem (or any lock for that matter).
This is racy. As such, use the get_user_pages_fast()
alternative and safely avoid taking the lock, if possible.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c
index 85bba43e7d5dc7638138f90f1eb0dd56609c5807..658a8e06a69bb541a4e659da84ca0cd8a65daf35 100644 (file)
--- a/arch/ia64/kernel/err_inject.c
+++ b/arch/ia64/kernel/err_inject.c
@@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev, struct device_attribute *attr,
        u64 virt_addr=simple_strtoull(buf, NULL, 16);
        int ret;
 
-       ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL);
+       ret = get_user_pages_fast(virt_addr, 1, FOLL_WRITE, NULL);
        if (ret<=0) {
 #ifdef ERR_INJ_DEBUG
                printk("Virtual address %lx is not existing.\n",virt_addr);