releases/4.14.53/powerpc-ptrace-fix-setting-512b-aligned-breakpoints-with-ptrace_set_debugreg.patch

   1 From 4f7c06e26ec9cf7fe9f0c54dc90079b6a4f4b2c3 Mon Sep 17 00:00:00 2001
   2 From: Michael Neuling <mikey@neuling.org>
   3 Date: Thu, 17 May 2018 15:37:15 +1000
   4 Subject: powerpc/ptrace: Fix setting 512B aligned breakpoints with PTRACE_SET_DEBUGREG
   5
   6 From: Michael Neuling <mikey@neuling.org>
   7
   8 commit 4f7c06e26ec9cf7fe9f0c54dc90079b6a4f4b2c3 upstream.
   9
  10 In commit e2a800beaca1 ("powerpc/hw_brk: Fix off by one error when
  11 validating DAWR region end") we fixed setting the DAWR end point to
  12 its max value via PPC_PTRACE_SETHWDEBUG. Unfortunately we broke
  13 PTRACE_SET_DEBUGREG when setting a 512 byte aligned breakpoint.
  14
  15 PTRACE_SET_DEBUGREG currently sets the length of the breakpoint to
  16 zero (memset() in hw_breakpoint_init()). This worked with
  17 arch_validate_hwbkpt_settings() before the above patch was applied but
  18 is now broken if the breakpoint is 512byte aligned.
  19
  20 This sets the length of the breakpoint to 8 bytes when using
  21 PTRACE_SET_DEBUGREG.
  22
  23 Fixes: e2a800beaca1 ("powerpc/hw_brk: Fix off by one error when validating DAWR region end")
  24 Cc: stable@vger.kernel.org # v3.11+
  25 Signed-off-by: Michael Neuling <mikey@neuling.org>
  26 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  arch/powerpc/kernel/ptrace.c |    1 +
  31  1 file changed, 1 insertion(+)
  32
  33 --- a/arch/powerpc/kernel/ptrace.c
  34 +++ b/arch/powerpc/kernel/ptrace.c
  35 @@ -2362,6 +2362,7 @@ static int ptrace_set_debugreg(struct ta
  36         /* Create a new breakpoint request if one doesn't exist already */
  37         hw_breakpoint_init(&attr);
  38         attr.bp_addr = hw_brk.address;
  39 +       attr.bp_len = 8;
  40         arch_bp_generic_fields(hw_brk.type,
  41                                &attr.bp_type);
  42