drivers/virt/fsl_hypervisor: Fix error handling path

First, when memory allocation for sg_list_unaligned failed, there
is a bug of calling put_pages() as we haven't pinned any pages.

Second, if get_user_pages_fast() failed we should unpin num_pinned
pages.

This will address both.

As part of these changes, minor update in documentation.

Fixes: 6db7199407ca ("drivers/virt: introduce Freescale hypervisor management driver")
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/1598995271-6755-1-git-send-email-jrdr.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
index 1b0b11b..46ee0a0 100644 (file)
--- a/drivers/virt/fsl_hypervisor.c
+++ b/drivers/virt/fsl_hypervisor.c
@@ -157,7 +157,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
 
        unsigned int i;
        long ret = 0;
-       int num_pinned; /* return value from get_user_pages() */
+       int num_pinned = 0; /* return value from get_user_pages_fast() */
        phys_addr_t remote_paddr; /* The next address in the remote buffer */
        uint32_t count; /* The number of bytes left to copy */
 
@@ -174,7 +174,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
                return -EINVAL;
 
        /*
-        * The array of pages returned by get_user_pages() covers only
+        * The array of pages returned by get_user_pages_fast() covers only
         * page-aligned memory.  Since the user buffer is probably not
         * page-aligned, we need to handle the discrepancy.
         *
@@ -224,7 +224,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
 
        /*
         * 'pages' is an array of struct page pointers that's initialized by
-        * get_user_pages().
+        * get_user_pages_fast().
         */
        pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
        if (!pages) {
@@ -241,7 +241,7 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
        if (!sg_list_unaligned) {
                pr_debug("fsl-hv: could not allocate S/G list\n");
                ret = -ENOMEM;
-               goto exit;
+               goto free_pages;
        }
        sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
 
@@ -250,7 +250,6 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
                num_pages, param.source != -1 ? FOLL_WRITE : 0, pages);
 
        if (num_pinned != num_pages) {
-               /* get_user_pages() failed */
                pr_debug("fsl-hv: could not lock source buffer\n");
                ret = (num_pinned < 0) ? num_pinned : -EFAULT;
                goto exit;
@@ -292,13 +291,13 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
                virt_to_phys(sg_list), num_pages);
 
 exit:
-       if (pages) {
-               for (i = 0; i < num_pages; i++)
-                       if (pages[i])
-                               put_page(pages[i]);
+       if (pages && (num_pinned > 0)) {
+               for (i = 0; i < num_pinned; i++)
+                       put_page(pages[i]);
        }
 
        kfree(sg_list_unaligned);
+free_pages:
        kfree(pages);
 
        if (!ret)