From b13d14339baaaa720e7e5448855f33ba501917aa Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Sun, 30 Oct 2016 23:19:24 +0100 Subject: [PATCH] ppdev: fix double-free of pp->pdev->name free_pardevice() is called by parport_unregister_device() and already frees pp->pdev->name, don't try to do it again. This bug causes kernel crashes. I found and verified this with KASAN and some added pr_emerg()s: [ 60.316568] pp_release: pp->pdev->name == ffff88039cb264c0 [ 60.316692] free_pardevice: freeing par_dev->name at ffff88039cb264c0 [ 60.316706] pp_release: kfree(ffff88039cb264c0) [ 60.316714] ========================================================== [ 60.316722] BUG: Double free or freeing an invalid pointer [ 60.316731] Unexpected shadow byte: 0xFB [ 60.316801] Object at ffff88039cb264c0, in cache kmalloc-32 size: 32 [ 60.316813] Allocated: [ 60.316824] PID = 1695 [ 60.316869] Freed: [ 60.316880] PID = 1695 [ 60.316935] ========================================================== Signed-off-by: Jann Horn Acked-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- drivers/char/ppdev.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c index d23368874710..6af1ce04b3da 100644 --- a/drivers/char/ppdev.c +++ b/drivers/char/ppdev.c @@ -748,10 +748,7 @@ static int pp_release(struct inode *inode, struct file *file) } if (pp->pdev) { - const char *name = pp->pdev->name; - parport_unregister_device(pp->pdev); - kfree(name); pp->pdev = NULL; pr_debug(CHRDEV "%x: unregistered pardevice\n", minor); } -- 2.30.2