From: Dan Carpenter dan.carpenter@oracle.com
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter dan.carpenter@oracle.com Reviewed-by: Oleksandr Tyshchenko oleksandr_tyshchenko@epam.com Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/xen/xenbus/xenbus_dev_frontend.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c @@ -122,7 +122,7 @@ static ssize_t xenbus_file_read(struct f { struct xenbus_file_priv *u = filp->private_data; struct read_buffer *rb; - unsigned i; + ssize_t i; int ret;
mutex_lock(&u->reply_mutex); @@ -142,7 +142,7 @@ again: rb = list_entry(u->read_buffers.next, struct read_buffer, list); i = 0; while (i < len) { - unsigned sz = min((unsigned)len - i, rb->len - rb->cons); + size_t sz = min_t(size_t, len - i, rb->len - rb->cons);
ret = copy_to_user(ubuf + i, &rb->msg[rb->cons], sz);