From 0969e00b3933a10a481f5bc13c834bf1abbc438d Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Fri, 7 Jan 2022 11:50:49 +0100 Subject: [PATCH] q800: fix segfault with invalid MacROM "qemu-system-m68k -M q800 -bios /dev/null" crashes with a segfault in q800_init(). This happens because the code doesn't check that rom_ptr() returned a non-NULL pointer . To avoid NULL pointer, don't allow 0 sized file and use bios_size with rom_ptr(). Resolves: https://gitlab.com/qemu-project/qemu/-/issues/756 Reported-by: Peter Maydell Signed-off-by: Laurent Vivier Reviewed-by: Thomas Huth Reviewed-by: Mark Cave-Ayland Message-Id: <20220107105049.961489-1-laurent@vivier.eu> Signed-off-by: Laurent Vivier --- hw/m68k/q800.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c index e4c7c9b88a..55dfe5036f 100644 --- a/hw/m68k/q800.c +++ b/hw/m68k/q800.c @@ -672,12 +672,13 @@ static void q800_init(MachineState *machine) /* Remove qtest_enabled() check once firmware files are in the tree */ if (!qtest_enabled()) { - if (bios_size < 0 || bios_size > MACROM_SIZE) { + if (bios_size <= 0 || bios_size > MACROM_SIZE) { error_report("could not load MacROM '%s'", bios_name); exit(1); } - ptr = rom_ptr(MACROM_ADDR, MACROM_SIZE); + ptr = rom_ptr(MACROM_ADDR, bios_size); + assert(ptr != NULL); stl_phys(cs->as, 0, ldl_p(ptr)); /* reset initial SP */ stl_phys(cs->as, 4, MACROM_ADDR + ldl_p(ptr + 4)); /* reset initial PC */