Commit fb1cc2f9 authored Aug 27, 2017 by Jan H. Schönherr Committed by Ingo Molnar Aug 29, 2017

x86/boot: Prevent faulty bootparams.screeninfo from causing harm



If a zero for the number of lines manages to slip through, scroll()
may underflow some offset calculations, causing accesses outside the
video memory.

Make the check in __putstr() more pessimistic to prevent that.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1503858223-14983-1-git-send-email-jschoenh@amazon.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 5746f055

arch/x86/boot/compressed/misc.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -116,8 +116,7 @@ void __putstr(const char *s)
		}
		}

		if (boot_params->screen_info.orig_video_mode == 0 &&
		lines == 0 && cols == 0)
		if (lines == 0 \|\| cols == 0)
		return;

		x = boot_params->screen_info.orig_x;