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authorJan H. Schönherr <jschoenh@amazon.de>2017-08-27 20:23:43 +0200
committerIngo Molnar <mingo@kernel.org>2017-08-29 13:32:50 +0200
commitfb1cc2f91664fd8a2e454970480b5413725919f1 (patch)
treefce72809a3f0b6248af9f98c0f98323163ef0b86
parent5746f0555d00e1cbb7bc20a2fd09041ace6f350c (diff)
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>
-rw-r--r--arch/x86/boot/compressed/misc.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index a0838ab929f2..c14217cd0155 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -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;