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    Subject[PATCH 5.9 236/757] drivers/virt/fsl_hypervisor: Fix error handling path
    Date
    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 1b0b11b55d2a0..46ee0a0998b6f 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 = 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)
    --
    2.25.1


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