On Fri, May 10, 2019 at 10:24:50PM +0800, Gen Zhang wrote: > On Fri, May 10, 2019 at 13:14:02PM +0800, Greg KH < > gre...@linuxfoundation.org> wrote: > >Note, your email client ate all of the tabs and made the patch > >impossible to apply, so please fix this up before you resend it. > > > >thanks, > > > >greg k-h > From: Gen Zhang <blackgod016...@gmail.com> > Date: Fri, 10 May 2019 09:31:30 +0000 > Subject: [PATCH] vt: Fix a missing-check bug in drivers/tty/vt/vt.c file of > Linux 5.0.14 > > Hi, > I found this missing-check bug in Linux-5.0.14/drivers/tty/vt/vt.c when I > was examining the source code. > > 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 be failed. > 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 an error. > > Below is the patch file, and I am ready to sumbit it to the kernel tree. > I am looking forward to a reply on this, thank you! > > Kind regards > Gen > > Signed-off-by: Gen Zhang <blackgod016...@gmail.com> > --- > > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -3322,10 +3322,14 @@ 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_cons[currcons].d || !vc) > + goto err_vc; > 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 err_vc_screenbuf; > vc_init(vc, vc->vc_rows, vc->vc_cols, > currcons || !vc->vc_sw->con_save_screen); > } > @@ -3347,6 +3351,14 @@ static int __init con_init(void) > register_console(&vt_console_driver); > #endif > return 0; > +err_vc: > + console_unlock(); > + return -ENOMEM; > +err_vc_screenbuf: > + console_unlock(); > + kfree(vc); > + vc_cons[currcons].d = NULL; > + return -ENOMEM; > } > console_initcall(con_init);
Still impossible to apply :( Also, what about Dave's response to you? This really can never be hit, like other early-init tty allocations that we do not check because of this issue, correct? thanks, greg k-h