On 3/24/20 2:35 PM, Chuhong Yuan wrote:

On Fri, Mar 20, 2020 at 8:01 PM Bartlomiej Zolnierkiewicz b.zolnierkie@samsung.com wrote:

...

On 3/10/20 3:35 AM, Chuhong Yuan wrote:

...

The driver forgets to free the I/O region in remove and probe failure. Add the missed calls to fix it.

Signed-off-by: Chuhong Yuan hslester96@gmail.com

Changes in v3:

• Revise the commit message.
• Add an error handler to suit the "goto error" before request_region().
• Revise the order of operations in remove.

drivers/video/fbdev/vesafb.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c index a1fe24ea869b..c7bc9ace47d4 100644 --- a/drivers/video/fbdev/vesafb.c +++ b/drivers/video/fbdev/vesafb.c @@ -439,7 +439,7 @@ static int vesafb_probe(struct platform_device *dev) "vesafb: abort, cannot ioremap video memory 0x%x @ 0x%lx\n", vesafb_fix.smem_len, vesafb_fix.smem_start); err = -EIO;

•         goto err;
  

•         goto err_release_region;
  }
  
  printk(KERN_INFO "vesafb: framebuffer at 0x%lx, mapped to 0x%p, "
  

@@ -458,15 +458,17 @@ static int vesafb_probe(struct platform_device *dev)

  if (fb_alloc_cmap(&info->cmap, 256, 0) < 0) {
          err = -ENOMEM;

•         goto err;
  

•         goto err_release_region;
  }
  if (register_framebuffer(info)<0) {
          err = -EINVAL;
          fb_dealloc_cmap(&info->cmap);
  

•         goto err;
  

•         goto err_release_region;
  }
  fb_info(info, "%s frame buffer device\n", info->fix.id);
  return 0;
  

+err_release_region:

• release_region(0x3c0, 32);
  

This is incorrect.

The cleanup order should be the reverse of the probing order.

Also request_region() return value is not checked by the driver (there is a comment that it can fail and is optional):

    /* request failure does not faze us, as vgacon probably has this
     * region already (FIXME) */
    request_region(0x3c0, 32, "vesafb");

so what would happen in such case? It seems that unconditionally doing the release will result in freeing the I/O region owned by the other driver (vgacon)..

Maybe we can add a field to represent whether the request succeeds? request_region() returns source *, we can store it and check whether it is null when we are going to call release_region().

Yes, this is a preferred approach.

Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics

...

...

err: arch_phys_wc_del(par->wc_cookie); if (info->screen_base) @@ -481,6 +483,7 @@ static int vesafb_remove(struct platform_device *pdev) struct fb_info *info = platform_get_drvdata(pdev);

  unregister_framebuffer(info);

• release_region(0x3c0, 32);
  framebuffer_release(info);
  
  return 0;
  
  

Best regards,

Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics