Messages in this thread | | | Date | Wed, 22 May 2019 10:18:54 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH v3] vt: Fix a missing-check bug in drivers/tty/vt/vt.c |
| |
On Wed, 22 May 2019, Gen Zhang wrote:
> In function con_init(), the pointer variable vc_cons[currcons].d, vc and > vc->vc_screenbuf is allocated a memory space via kzalloc(). And they are > used in the following codes. > However, when there is a memory allocation error, kzalloc() can fail. > Thus null pointer (vc_cons[currcons].d, vc and vc->vc_screenbuf) > dereference may happen. And it will cause the kernel to crash. Therefore, > we should check return value and handle the error. > Further, since the allcoation is in a loop, we should free all the > allocated memory in a loop. > > Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
> > --- > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > index fdd12f8..d50f68f 100644 > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -3350,10 +3350,14 @@ static int __init con_init(void) > > for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) { > vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT); > + if (!vc) > + goto fail1; > INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK); > tty_port_init(&vc->port); > visual_init(vc, currcons, 1); > vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT); > + if (!vc->vc_screenbuf) > + goto fail2; > vc_init(vc, vc->vc_rows, vc->vc_cols, > currcons || !vc->vc_sw->con_save_screen); > } > @@ -3375,6 +3379,16 @@ static int __init con_init(void) > register_console(&vt_console_driver); > #endif > return 0; > +fail1: > + while (currcons > 0) { > + currcons--; > + kfree(vc_cons[currcons].d->vc_screenbuf); > +fail2: > + kfree(vc_cons[currcons].d); > + vc_cons[currcons].d = NULL; > + } > + console_unlock(); > + return -ENOMEM; > } > console_initcall(con_init); > > --- >
| |