Messages in this thread Patch in this message | | | Date | Wed, 25 Jan 2017 18:23:21 +0100 | From | Borislav Petkov <> | Subject | Re: x86/microcode: use-after-free after cpu offline/online |
| |
On Wed, Jan 25, 2017 at 07:58:39PM +0300, Andrey Ryabinin wrote: > On 4.10-rc5 > # echo 0 > /sys/devices/system/cpu/cpu1/online > # echo 1 > /sys/devices/system/cpu/cpu1/online > > triggers use-after-free (probably caused by 06b8534cb72 "x86/microcode: Rework microcode loading"). > > __load_ucode_intel() accesses initrd which is obviously gone at this point:
Does that help?
--- diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 2af69d27da62..fdbf8d29ffcf 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -248,8 +248,12 @@ struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa) * possibly relocates the ramdisk. In either case, initrd_start contains * the updated address so use that instead. */ - if (!use_pa && initrd_start) - start = initrd_start; + if (!use_pa) { + if (initrd_start) + start = initrd_start; + else + return (struct cpio_data){ NULL, 0, "" }; + } return find_cpio_data(path, (void *)start, size, NULL); #else /* !CONFIG_BLK_DEV_INITRD */ -- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
| |