[PATCH 4.9 039/139] drivers/virt/fsl_hypervisor: Fix error handling path

Greg Kroah-Hartman
2020-10-27T14:11:15Z

From: Souptick Joarder <jrdr.linux@gmail.com>

[ Upstream commit 7f360bec37857bfd5a48cef21d86f58a09a3df63 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/virt/fsl_hypervisor.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
index 732e9abdcf969..29b9680035258 100644
--- 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 = kzalloc(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));

@@ -253,7 +253,6 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
up_read(&current->mm->mmap_sem);

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;
@@ -295,13 +294,13 @@ 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)
--
2.25.1