BMC/Intel-BMC/linux.git/arch/x86/kernel/cpu/microcode, branch dev-4.10

x86/microcode: Do not access the initrd after it has been freed

2017-01-30T08:32:42+00:00

When we look for microcode blobs, we first try builtin and if that doesn't succeed, we fallback to the initrd supplied to the kernel. However, at some point doing boot, that initrd gets jettisoned and we shouldn't access it anymore. But we do, as the below KASAN report shows. That's because find_microcode_in_initrd() doesn't check whether the initrd is still valid or not. So do that. ================================================================== BUG: KASAN: use-after-free in find_cpio_data Read of size 1 by task swapper/1/0 page:ffffea0000db9d40 count:0 mapcount:0 mapping: (null) index:0x1 flags: 0x100000000000000() raw: 0100000000000000 0000000000000000 0000000000000001 00000000ffffffff raw: dead000000000100 dead000000000200 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W 4.10.0-rc5-debug-00075-g2dbde22 #3 Hardware name: Dell Inc. XPS 13 9360/0839Y6, BIOS 1.2.3 12/01/2016 Call Trace: dump_stack ? _atomic_dec_and_lock ? __dump_page kasan_report_error ? pointer ? find_cpio_data __asan_report_load1_noabort ? find_cpio_data find_cpio_data ? vsprintf ? dump_stack ? get_ucode_user ? print_usage_bug find_microcode_in_initrd __load_ucode_intel ? collect_cpu_info_early ? debug_check_no_locks_freed load_ucode_intel_ap ? collect_cpu_info ? trace_hardirqs_on ? flat_send_IPI_mask_allbutself load_ucode_ap ? get_builtin_firmware ? flush_tlb_func ? do_raw_spin_trylock ? cpumask_weight cpu_init ? trace_hardirqs_off ? play_dead_common ? native_play_dead ? hlt_play_dead ? syscall_init ? arch_cpu_idle_dead ? do_idle start_secondary start_cpu Memory state around the buggy address: ffff880036e74f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff880036e74f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff880036e75000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff880036e75080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff880036e75100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== Reported-by: Andrey Ryabinin Tested-by: Andrey Ryabinin Signed-off-by: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170126165833.evjemhbqzaepirxo@pd.tnic Signed-off-by: Ingo Molnar

x86/microcode/intel: Drop stashed AP patch pointer optimization

2017-01-23T08:39:55+00:00

This was meant to save us the scanning of the microcode containter in the initrd since the first AP had already done that but it can also hurt us: Imagine a single hyperthreaded CPU (Intel(R) Atom(TM) CPU N270, for example) which updates the microcode on the BSP but since the microcode engine is shared between the two threads, the update on CPU1 doesn't happen because it has already happened on CPU0 and we don't find a newer microcode revision on CPU1. Which doesn't set the intel_ucode_patch pointer and at initrd jettisoning time we don't save the microcode patch for later application. Now, when we suspend to RAM, the loaded microcode gets cleared so we need to reload but there's no patch saved in the cache. Removing the optimization fixes this issue and all is fine and dandy. Fixes: 06b8534cb728 ("x86/microcode: Rework microcode loading") Signed-off-by: Borislav Petkov Reviewed-by: Thomas Gleixner Link: http://lkml.kernel.org/r/20170120202955.4091-2-bp@alien8.de Signed-off-by: Thomas Gleixner

x86/microcode/intel: Use correct buffer size for saving microcode data

2017-01-09T22:11:15+00:00

In generic_load_microcode(), curr_mc_size is the size of the last allocated buffer and since we have this performance "optimization" there to vmalloc a new buffer only when the current one is bigger, curr_mc_size ends up becoming the size of the biggest buffer we've seen so far. However, we end up saving the microcode patch which matches our CPU and its size is not curr_mc_size but the respective mc_size during the iteration while we're staring at it. So save that mc_size into a separate variable and use it to store the previously found microcode buffer. Without this fix, we could get oops like this: BUG: unable to handle kernel paging request at ffffc9000e30f000 IP: __memcpy+0x12/0x20 ... Call Trace: ? kmemdup+0x43/0x60 __alloc_microcode_buf+0x44/0x70 save_microcode_patch+0xd4/0x150 generic_load_microcode+0x1b8/0x260 request_microcode_user+0x15/0x20 microcode_write+0x91/0x100 __vfs_write+0x34/0x120 vfs_write+0xc1/0x130 SyS_write+0x56/0xc0 do_syscall_64+0x6c/0x160 entry_SYSCALL64_slow_path+0x25/0x25 Fixes: 06b8534cb728 ("x86/microcode: Rework microcode loading") Signed-off-by: Jun'ichi Nomura Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/4f33cbfd-44f2-9bed-3b66-7446cd14256f@ce.jp.nec.com Signed-off-by: Thomas Gleixner

x86/microcode/intel: Fix allocation size of struct ucode_patch

2017-01-09T22:11:14+00:00

We allocate struct ucode_patch here. @size is the size of microcode data and used for kmemdup() later in this function. Fixes: 06b8534cb728 ("x86/microcode: Rework microcode loading") Signed-off-by: Jun'ichi Nomura Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/7a730dc9-ac17-35c4-fe76-dfc94e5ecd95@ce.jp.nec.com Signed-off-by: Thomas Gleixner

x86/microcode/intel: Add a helper which gives the microcode revision

2017-01-09T22:11:14+00:00

Since on Intel we're required to do CPUID(1) first, before reading the microcode revision MSR, let's add a special helper which does the required steps so that we don't forget to do them next time, when we want to read the microcode revision. Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/20170109114147.5082-4-bp@alien8.de Signed-off-by: Thomas Gleixner

x86/microcode: Use native CPUID to tickle out microcode revision

2017-01-09T22:11:14+00:00

Intel supplies the microcode revision value in MSR 0x8b (IA32_BIOS_SIGN_ID) after CPUID(1) has been executed. Execute it each time before reading that MSR. It used to do sync_core() which did do CPUID but c198b121b1a1 ("x86/asm: Rewrite sync_core() to use IRET-to-self") changed the sync_core() implementation so we better make the microcode loading case explicit, as the SDM documents it. Reported-and-tested-by: Jun'ichi Nomura Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/20170109114147.5082-3-bp@alien8.de Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Reload proper initrd start address

2016-12-21T09:50:04+00:00

When we switch to virtual addresses and, especially after reserve_initrd()->relocate_initrd() have run, we have the updated initrd address in initrd_start. Use initrd_start then instead of the address which has been passed to us through boot params. (That still gets used when we're running the very early routines on the BSP). Reported-and-tested-by: Boris Ostrovsky Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/20161220144012.lc4cwrg6dphqbyqu@pd.tnic Signed-off-by: Thomas Gleixner

x86/microcode/intel: Replace sync_core() with native_cpuid()

2016-12-19T10:54:21+00:00

The Intel microcode driver is using sync_core() to mean "do CPUID with EAX=1". I want to rework sync_core(), but first the Intel microcode driver needs to stop depending on its current behavior. Reported-by: Henrique de Moraes Holschuh Signed-off-by: Andy Lutomirski Acked-by: Borislav Petkov Cc: Juergen Gross Cc: One Thousand Gnomes Cc: Peter Zijlstra Cc: Brian Gerst Cc: Matthew Whitehead Cc: Andrew Cooper Cc: Boris Ostrovsky Cc: xen-devel Link: http://lkml.kernel.org/r/535a025bb91fed1a019c5412b036337ad239e5bb.1481307769.git.luto@kernel.org Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Use native_cpuid() in load_ucode_amd_bsp()

2016-12-19T09:46:20+00:00

When CONFIG_PARAVIRT is selected, cpuid() becomes a call. Since for 32-bit kernels load_ucode_amd_bsp() is executed before paging is enabled the call cannot be completed (as kernel virtual addresses are not reachable yet). Use native_cpuid() instead which is an asm wrapper for the CPUID instruction. Signed-off-by: Boris Ostrovsky Signed-off-by: Borislav Petkov Cc: Jürgen Gross Link: http://lkml.kernel.org/r/1481906392-3847-1-git-send-email-boris.ostrovsky@oracle.com Link: http://lkml.kernel.org/r/20161218164414.9649-5-bp@alien8.de Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Do not load when running on a hypervisor

2016-12-19T09:46:20+00:00

Doing so is completely void of sense for multiple reasons so prevent it. Set dis_ucode_ldr to true and thus disable the microcode loader by default to address xen pv guests which execute the AP path but not the BSP path. By having it turned off by default, the APs won't run into the loader either. Also, check CPUID(1).ECX[31] which hypervisors set. Well almost, not the xen pv one. That one gets the aforementioned "fix". Also, improve the detection method by caching the final decision whether to continue loading in dis_ucode_ldr and do it once on the BSP. The APs then simply test that value. Signed-off-by: Borislav Petkov Tested-by: Juergen Gross Tested-by: Boris Ostrovsky Acked-by: Juergen Gross Link: http://lkml.kernel.org/r/20161218164414.9649-4-bp@alien8.de Signed-off-by: Thomas Gleixner