Blame SOURCES/0063-hexdump.h-fix-arithmetic-error.patch

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From 9313a515432ba938e66f2edc1e22d548fed1eb5c Mon Sep 17 00:00:00 2001
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From: Peter Jones <pjones@redhat.com>
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Date: Thu, 30 Jul 2020 14:34:22 -0400
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Subject: [PATCH] hexdump.h: fix arithmetic error.
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When I modified the hexdumper to help debug MokListRT mirroring not
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working because of PcdMaxVolatileVariableSize being tiny, I
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inadvertently added something that is effectively:
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hexdump(..., char *buf, ..., int position)
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{
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	unsigned long begin = (position % 16);
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	unsigned long i;
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	...
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	for (i = 0; i < begin; i++) {
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		...
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	}
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	...
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}
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Unfortunately, in c if 0x8 is set in position, that means begin is
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0xfffffffffffff8, because signed integer math is horrifying:
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include/hexdump.h:99:vhexdumpf() &data[offset]:0x9E77E6BC size-offset:0x14
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include/hexdump.h:15:prepare_hex() position:0x9E77E6BC
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include/hexdump.h:17:prepare_hex() before:0xFFFFFFFFFFFFFFFC size:0x14
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include/hexdump.h:19:prepare_hex() before:0xFFFFFFFFFFFFFFFC after:0x0
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include/hexdump.h:21:prepare_hex() buf:0x000000009E77E2BC offset:0 &buf[offset]:0x000000009E77E2BC
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Woops.
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This could further have been prevented in /some/ cases by simply not
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preparing the hexdump buffer when "verbose" is disabled.
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This patch makes "pos" be unsigned in all cases, and also checks for
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verbose in vhexdumpf() and simply returns if it is 0.
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Signed-off-by: Peter Jones <pjones@redhat.com>
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---
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 include/hexdump.h | 7 +++++--
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 1 file changed, 5 insertions(+), 2 deletions(-)
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diff --git a/include/hexdump.h b/include/hexdump.h
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index f3f3ac284a3..b2968cd4f85 100644
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--- a/include/hexdump.h
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+++ b/include/hexdump.h
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@@ -4,7 +4,7 @@
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 #include <stdint.h>
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 static inline unsigned long UNUSED
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-prepare_hex(const void *data, size_t size, char *buf, int position)
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+prepare_hex(const void *data, size_t size, char *buf, unsigned int position)
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 {
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 	char hexchars[] = "0123456789abcdef";
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 	int offset = 0;
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@@ -48,7 +48,7 @@ prepare_hex(const void *data, size_t size, char *buf, int position)
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 #define isprint(c) ((c) >= 0x20 && (c) <= 0x7e)
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 static inline void UNUSED
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-prepare_text(const void *data, size_t size, char *buf, int position)
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+prepare_text(const void *data, size_t size, char *buf, unsigned int position)
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 {
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 	int offset = 0;
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 	unsigned long i;
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@@ -84,6 +84,9 @@ vhexdumpf(const char *file, int line, const char *func, const CHAR16 * const fmt
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 	unsigned long display_offset = at;
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 	unsigned long offset = 0;
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+	if (verbose == 0)
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+		return;
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+
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 	while (offset < size) {
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 		char hexbuf[49];
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 		char txtbuf[19];
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-- 
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2.26.2
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