Commit 7174e54c authored by Jan Kiszka's avatar Jan Kiszka Committed by Gleb Natapov
Browse files

kvmvapic: Prevent reading beyond the end of guest RAM 



rom_state_paddr is guest provided (caller address of outw(VAPIC_PORT) +
writen 16-bit value) and can be influenced to point beyond the end of
the host memory backing the guest's RAM. Make sure we do not use this
pointer to actually read beyond the limits.

Reading arbitrary guest bytes is harmless, the guest kernel has to
manage access to this I/O port anyway.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 2560f19f

hw/i386/kvmvapic.c

+3 −0
Original line number Diff line number Diff line
@@ -596,6 +596,9 @@ static int vapic_map_rom_writable(VAPICROMState *s) 
    section = memory_region_find(as, 0, 1);



    /* read ROM size from RAM region */

    if (rom_paddr + 2 >= memory_region_size(section.mr)) {

        return -1;

    }

    ram = memory_region_get_ram_ptr(section.mr);

    rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE;

    if (rom_size == 0) {