linux-kernel - [PATCH 4.4 048/105] ARM: 8764/1: kgdb: fix NUMREGBYTES so that gdb

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Message-Id: <20180701153152.780979690@linuxfoundation.org>
Date:   Sun,  1 Jul 2018 18:01:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Rivshin <drivshin@...worx.com>,
        Rabin Vincent <rabin@....in>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH 4.4 048/105] ARM: 8764/1: kgdb: fix NUMREGBYTES so that gdb_regs[] is the correct size

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Rivshin <DRivshin@...worx.com>

commit 76ed0b803a2ab793a1b27d1dfe0de7955282cd34 upstream.

NUMREGBYTES (which is used as the size for gdb_regs[]) is incorrectly
based on DBG_MAX_REG_NUM instead of GDB_MAX_REGS. DBG_MAX_REG_NUM
is the number of total registers, while GDB_MAX_REGS is the number
of 'unsigned longs' it takes to serialize those registers. Since
FP registers require 3 'unsigned longs' each, DBG_MAX_REG_NUM is
smaller than GDB_MAX_REGS.

This causes GDB 8.0 give the following error on connect:
"Truncated register 19 in remote 'g' packet"

This also causes the register serialization/deserialization logic
to overflow gdb_regs[], overwriting whatever follows.

Fixes: 834b2964b7ab ("kgdb,arm: fix register dump")
Cc: <stable@...r.kernel.org> # 2.6.37+
Signed-off-by: David Rivshin <drivshin@...worx.com>
Acked-by: Rabin Vincent <rabin@....in>
Tested-by: Daniel Thompson <daniel.thompson@...aro.org>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/include/asm/kgdb.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -76,7 +76,7 @@ extern int kgdb_fault_expected;
 
 #define KGDB_MAX_NO_CPUS	1
 #define BUFMAX			400
-#define NUMREGBYTES		(DBG_MAX_REG_NUM << 2)
+#define NUMREGBYTES		(GDB_MAX_REGS << 2)
 #define NUMCRITREGBYTES		(32 << 2)
 
 #define _R0			0