It is 0 because for !0 values we would have exited already.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1457345404-28884-6-git-send-email-bp@alien8.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Turn them into proper sentences. Add comments to microcode_sanity_check() to
explain what it does.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1457345404-28884-5-git-send-email-bp@alien8.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Merge the two consecutive "if (ext_table_size)". No functional change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1457345404-28884-4-git-send-email-bp@alien8.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

sizeof(u32) is perfectly clear as it is.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1457345404-28884-3-git-send-email-bp@alien8.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Microcode checksum verification should be done using unsigned 32-bit
values otherwise the calculation overflow results in undefined
behaviour.

This is also nicely documented in the SDM, section "Microcode Update
Checksum":

  "To check for a corrupt microcode update, software must perform a
  unsigned DWORD (32-bit) checksum of the microcode update. Even though
  some fields are signed, the checksum procedure treats all DWORDs as
  unsigned. Microcode updates with a header version equal to 00000001H
  must sum all DWORDs that comprise the microcode update. A valid
  checksum check will yield a value of 00000000H."

but for some reason the code has been using ints from the very
beginning.

In practice, this bug possibly manifested itself only when doing the
microcode data checksum - apparently, currently shipped Intel microcode
doesn't have an extended signature table for which we do checksum
verification too.

  UBSAN: Undefined behaviour in arch/x86/kernel/cpu/microcode/intel_lib.c:105:12
  signed integer overflow:
  -1500151068 + -2125470173 cannot be represented in type 'int'
  CPU: 0 PID: 0 Comm: swapper Not tainted 4.5.0-rc5+ #495
  ...
  Call Trace:
   dump_stack
   ? inotify_ioctl
   ubsan_epilogue
   handle_overflow
   __ubsan_handle_add_overflow
   microcode_sanity_check
   get_matching_model_microcode.isra.2.constprop.8
   ? early_idt_handler_common
   ? strlcpy
   ? find_cpio_data
   load_ucode_intel_bsp
   load_ucode_bsp
   ? load_ucode_bsp
   x86_64_start_kernel

[ Expand and massage commit message. ]
Signed-off-by: NChris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: hmh@hmh.eng.br
Link: http://lkml.kernel.org/r/1456834359-5132-1-git-send-email-chris.bainbridge@gmail.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Remove the remaining module functionality leftovers. Make
"dis_ucode_ldr" an early_param and make it static again. Drop
module aliases, autoloading table, description, etc.

Bump version number, while at it.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1445334889-300-4-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

... to find_matching_signature() which is exactly what it does.

No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431860101-14847-5-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Unclutter function, make it a bit more readable, drop local
variables.

No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431860101-14847-4-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Drop unreadable macro, deconstruct compound conditional
statement into single ones and return early if they match. Add
comments.

There should be no functionality change resulting from this
patch.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431860101-14847-3-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

... to has_newer_microcode() as it does exactly that: checks
whether binary data @mc has newer microcode patch than the
applied one. Move @mc to be the first function arg too.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431860101-14847-2-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

@rev wasn't used in get_matching_sig(), drop it.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

It is a one-liner for checking microcode header revisions. On top of
that, it can be used wrong as it was the case in _save_mc(). Get rid of
it.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

... arguments list so that it comes more natural for those functions to
have the signature, processor flags and revision together, before the
rest of the args.

No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>

... to revision_is_newer() and push it up into the header and make it an
inline function.
Signed-off-by: NBorislav Petkov <bp@suse.de>

We've grown a bunch of microcode loader files all prefixed with
"microcode_". They should be under cpu/ because this is strictly
CPU-related functionality so do that and drop the prefix since they're
in their own directory now which gives that prefix. :)

While at it, drop MICROCODE_INTEL_LIB config item and stash the
functionality under CONFIG_MICROCODE_INTEL as it was its only user.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Tested-by: NAravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>

Define interfaces microcode_sanity_check() and get_matching_microcode(). They
are called both in early boot time and in microcode Intel driver.
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1356075872-3054-7-git-send-email-fenghua.yu@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>