If not caught early, a zero-length ROM will cause a NULL-pointer access later on in patch_hypercalls when allocating a zero-length ROM copy and trying to read from it.
CC: qemu-sta...@nongnu.org Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> --- hw/i386/kvmvapic.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c index 15beb80..7ac0fe1 100644 --- a/hw/i386/kvmvapic.c +++ b/hw/i386/kvmvapic.c @@ -578,7 +578,7 @@ static int patch_hypercalls(VAPICROMState *s) * enable write access to the option ROM so that variables can be updated by * the guest. */ -static void vapic_map_rom_writable(VAPICROMState *s) +static int vapic_map_rom_writable(VAPICROMState *s) { hwaddr rom_paddr = s->rom_state_paddr & ROM_BLOCK_MASK; MemoryRegionSection section; @@ -599,6 +599,9 @@ static void vapic_map_rom_writable(VAPICROMState *s) /* read ROM size from RAM region */ ram = memory_region_get_ram_ptr(section.mr); rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE; + if (rom_size == 0) { + return -1; + } s->rom_size = rom_size; /* We need to round to avoid creating subpages @@ -612,11 +615,15 @@ static void vapic_map_rom_writable(VAPICROMState *s) memory_region_add_subregion_overlap(as, rom_paddr, &s->rom, 1000); s->rom_mapped_writable = true; memory_region_unref(section.mr); + + return 0; } static int vapic_prepare(VAPICROMState *s) { - vapic_map_rom_writable(s); + if (vapic_map_rom_writable(s) < 0) { + return -1; + } if (patch_hypercalls(s) < 0) { return -1; -- 1.8.1.1.298.ge7eed54 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html