video: fbdev: w100fb: Fix a potential double free.

commit 18722d48a6bb9c2e8d046214c0a5fd19d0a7c9f6 upstream.

Some memory is vmalloc'ed in the 'w100fb_save_vidmem' function and freed in
the 'w100fb_restore_vidmem' function. (these functions are called
respectively from the 'suspend' and the 'resume' functions)

However, it is also freed in the 'remove' function.

In order to avoid a potential double free, set the corresponding pointer
to NULL once freed in the 'w100fb_restore_vidmem' function.

Fixes: aac51f09d96a ("[PATCH] w100fb: Rewrite for platform independence")
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Antonino Daplas <adaplas@pol.net>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: <stable@vger.kernel.org> # v2.6.14+
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200506181902.193290-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/video/fbdev/w100fb.c b/drivers/video/fbdev/w100fb.c
index 10951c8..7bd4c27 100644 (file)
--- a/drivers/video/fbdev/w100fb.c
+++ b/drivers/video/fbdev/w100fb.c
@@ -583,6 +583,7 @@ static void w100fb_restore_vidmem(struct w100fb_par *par)
                memsize=par->mach->mem->size;
                memcpy_toio(remapped_fbuf + (W100_FB_BASE-MEM_WINDOW_BASE), par->saved_extmem, memsize);
                vfree(par->saved_extmem);
+               par->saved_extmem = NULL;
        }
        if (par->saved_intmem) {
                memsize=MEM_INT_SIZE;
@@ -591,6 +592,7 @@ static void w100fb_restore_vidmem(struct w100fb_par *par)
                else
                        memcpy_toio(remapped_fbuf + (W100_FB_BASE-MEM_WINDOW_BASE), par->saved_intmem, memsize);
                vfree(par->saved_intmem);
+               par->saved_intmem = NULL;
        }
 }