On 15.06.2018 09:13, Cornelia Huck wrote: > On Thu, 14 Jun 2018 21:08:43 +0200 > Thomas Huth <[email protected]> wrote: > >> On 11.06.2018 19:26, Thomas Huth wrote: >>> Add a sanity checks to fix the following two crashes: >>> >>> $ echo "Insane in the mainframe" > /tmp/test.txt >>> $ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -append xyz >>> Segmentation fault (core dumped) >>> $ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -initrd >>> /tmp/test.txt >>> Segmentation fault (core dumped) >>> >>> Signed-off-by: Thomas Huth <[email protected]> >>> --- >>> v2: Fixed 2nd crash with -initrd >>> >>> hw/s390x/ipl.c | 9 ++++++--- >>> 1 file changed, 6 insertions(+), 3 deletions(-) >>> >>> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c >>> index 04245b5..2ff8f20 100644 >>> --- a/hw/s390x/ipl.c >>> +++ b/hw/s390x/ipl.c >>> @@ -168,7 +168,8 @@ static void s390_ipl_realize(DeviceState *dev, Error >>> **errp) >>> * we can not rely on the ELF entry point - it was 0x800 (the >>> SALIPL >>> * loader) and it won't work. For this case we force it to >>> 0x10000, too. >>> */ >>> - if (pentry == KERN_IMAGE_START || pentry == 0x800) { >>> + if ((pentry == KERN_IMAGE_START || pentry == 0x800) && >>> + kernel_size > KERN_PARM_AREA + strlen(ipl->cmdline)) { >>> ipl->start_addr = KERN_IMAGE_START; >>> /* Overwrite parameters in the kernel image, which are "rom" */ >>> strcpy(rom_ptr(KERN_PARM_AREA), ipl->cmdline); >>> @@ -195,8 +196,10 @@ static void s390_ipl_realize(DeviceState *dev, Error >>> **errp) >>> * we have to overwrite values in the kernel image, >>> * which are "rom" >>> */ >>> - stq_p(rom_ptr(INITRD_PARM_START), initrd_offset); >>> - stq_p(rom_ptr(INITRD_PARM_SIZE), initrd_size); >>> + if (kernel_size > INITRD_PARM_SIZE + 8) { >>> + stq_p(rom_ptr(INITRD_PARM_START), initrd_offset); >>> + stq_p(rom_ptr(INITRD_PARM_SIZE), initrd_size); >>> + } >>> } >>> } >>> /* >> >> I just had to discover that this breaks the argv handling in >> kvm-unit-tests. Cornelia, could you please unqueue this patch again? >> I'll try to come up with a better solution... > > Argh. I wonder why?
kvm-unit-tests are ELF files which are not loaded to address 0, but still use the same entry point as Linux (0x10000) to be able to use the "--append" option of QEMU. Thus the check "kernel_size > KERN_PARM_AREA + strlen(ipl->cmdline)" does not work here. We'd need something like "start_addr + kernel_size > KERN_PARM_AREA + strlen(ipl->cmdline)" instead - but this does not make too much sense with ELF files that have multiple segments either. The correct fix is to check the size when calling rom_ptr() instead. I just sent a patch that does this. Thomas
