* [PATCH] x86/boot: Prevent faulty bootparams.screeninfo from causing harm
@ 2017-08-27 18:23 Jan H. Schönherr
0 siblings, 0 replies; only message in thread
From: Jan H. Schönherr @ 2017-08-27 18:23 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Thomas Gleixner, Ingo Molnar, linux-kernel, Jan H. Schönherr
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>
---
arch/x86/boot/compressed/misc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index a0838ab..c14217c 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;
--
2.3.1.dirty
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