Re: [PATCH] [video/fbdev] mbxfb_remove: fix null pointer dereference

On Sun, Jul 26, 2020 at 8:26 AM Gaurav Singh gaurav1086@gmail.com wrote:

Function mbxfb_debugfs_remove() accesses fbi->par without NULL check, hence do the NULL check in the caller mbxfb_remove().

...

@@ -1012,11 +1012,10 @@ static int mbxfb_remove(struct platform_device *dev)

    write_reg_dly(SYSRST_RST, SYSRST);

•   mbxfb_debugfs_remove(fbi);
  

    if (fbi) {

Can you explain how this is NULL on ->remove()?

I bet this check is simply redundant. But you have to check and update commit message accordingly.

            struct mbxfb_info *mfbi = fbi->par;

•           mbxfb_debugfs_remove(fbi);
            unregister_framebuffer(fbi);
            if (mfbi) {
                    if (mfbi->platform_remove)