BugLink: https://bugs.launchpad.net/bugs/1784382

commit 76ed0b80 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: 834b2964 ("kgdb,arm: fix register dump")
Cc: <stable@vger.kernel.org> # 2.6.37+
Signed-off-by: David Rivshin <drivshin@allworx.com>
Acked-by: Rabin Vincent <rabin@rab.in>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>