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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 <peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220107105049.961489-1-laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Laurent Vivier 2022-01-07 11:50:49 +01:00
parent 214bdf8e71
commit 0969e00b39
1 changed files with 3 additions and 2 deletions
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5
hw/m68k/q800.c
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@ -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 */