upstream: [media] wl128x: do not call copy_to_user() while holding spinlocks

copy_to_user() must not be called with spinlocks held, but it is in
fmc_transfer_rds_from_internal_buff().
The patch copies data to tmpbuf, releases spinlock and then passes it to userspace.
By the way there is a small unification: replace a couple of hardcoded constants by a macro.
Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/radio/wl128x/fmdrv_common.c b/drivers/media/radio/wl128x/fmdrv_common.c
index a002234..253f307 100644 (file)
--- a/drivers/media/radio/wl128x/fmdrv_common.c
+++ b/drivers/media/radio/wl128x/fmdrv_common.c
@@ -715,7 +715,7 @@ static void fm_irq_handle_rdsdata_getcmd_resp(struct fmdev *fmdev)
        struct fm_rdsdata_format rds_fmt;
        struct fm_rds *rds = &fmdev->rx.rds;
        unsigned long group_idx, flags;
-       u8 *rds_data, meta_data, tmpbuf[3];
+       u8 *rds_data, meta_data, tmpbuf[FM_RDS_BLK_SIZE];
        u8 type, blk_idx;
        u16 cur_picode;
        u32 rds_len;
@@ -1073,6 +1073,7 @@ int fmc_transfer_rds_from_internal_buff(struct fmdev *fmdev, struct file *file,
                u8 __user *buf, size_t count)
 {
        u32 block_count;
+       u8 tmpbuf[FM_RDS_BLK_SIZE];
        unsigned long flags;
        int ret;
 
@@ -1087,29 +1088,32 @@ int fmc_transfer_rds_from_internal_buff(struct fmdev *fmdev, struct file *file,
        }
 
        /* Calculate block count from byte count */
-       count /= 3;
+       count /= FM_RDS_BLK_SIZE;
        block_count = 0;
        ret = 0;
 
-       spin_lock_irqsave(&fmdev->rds_buff_lock, flags);
-
        while (block_count < count) {
-               if (fmdev->rx.rds.wr_idx == fmdev->rx.rds.rd_idx)
-                       break;
+               spin_lock_irqsave(&fmdev->rds_buff_lock, flags);
 
-               if (copy_to_user(buf, &fmdev->rx.rds.buff[fmdev->rx.rds.rd_idx],
-                                       FM_RDS_BLK_SIZE))
+               if (fmdev->rx.rds.wr_idx == fmdev->rx.rds.rd_idx) {
+                       spin_unlock_irqrestore(&fmdev->rds_buff_lock, flags);
                        break;
-
+               }
+               memcpy(tmpbuf, &fmdev->rx.rds.buff[fmdev->rx.rds.rd_idx],
+                                       FM_RDS_BLK_SIZE);
                fmdev->rx.rds.rd_idx += FM_RDS_BLK_SIZE;
                if (fmdev->rx.rds.rd_idx >= fmdev->rx.rds.buf_size)
                        fmdev->rx.rds.rd_idx = 0;
 
+               spin_unlock_irqrestore(&fmdev->rds_buff_lock, flags);
+
+               if (copy_to_user(buf, tmpbuf, FM_RDS_BLK_SIZE))
+                       break;
+
                block_count++;
                buf += FM_RDS_BLK_SIZE;
                ret += FM_RDS_BLK_SIZE;
        }
-       spin_unlock_irqrestore(&fmdev->rds_buff_lock, flags);
        return ret;
 }