diff options
| author | Dave Hansen <dave.hansen@linux.intel.com> | 2015-11-30 16:31:13 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-31 11:23:30 -0800 |
| commit | c24eedeca7b86abc1719f1705de671cee8853b8d (patch) | |
| tree | c1d4ce4a34eef8c2c9888ba0c5b9d35abfa72b2d /arch/x86 | |
| parent | 99c5a856dcee7658ec7e250aa477a9afaab8cfc6 (diff) | |
x86/mpx: Fix instruction decoder condition
commit 8e8efe0379bd93e8219ca0fc6fa80b5dd85b09cb upstream.
MPX decodes instructions in order to tell which bounds register
was violated. Part of this decoding involves looking at the "REX
prefix" which is a special instrucion prefix used to retrofit
support for new registers in to old instructions.
The X86_REX_*() macros are defined to return actual bit values:
#define X86_REX_R(rex) ((rex) & 4)
*not* boolean values. However, the MPX code was checking for
them like they were booleans. This might have led to us
mis-decoding the "REX prefix" and giving false information out to
userspace about bounds violations. X86_REX_B() actually is bit 1,
so this is really only broken for the X86_REX_X() case.
Fix the conditionals up to tolerate the non-boolean values.
Fixes: fcc7ffd67991 "x86, mpx: Decode MPX instruction to get bound violation information"
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20151201003113.D800C1E0@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/mm/mpx.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 4d1c11c07fe1..f738c61bc891 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -120,19 +120,19 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, switch (type) { case REG_TYPE_RM: regno = X86_MODRM_RM(insn->modrm.value); - if (X86_REX_B(insn->rex_prefix.value) == 1) + if (X86_REX_B(insn->rex_prefix.value)) regno += 8; break; case REG_TYPE_INDEX: regno = X86_SIB_INDEX(insn->sib.value); - if (X86_REX_X(insn->rex_prefix.value) == 1) + if (X86_REX_X(insn->rex_prefix.value)) regno += 8; break; case REG_TYPE_BASE: regno = X86_SIB_BASE(insn->sib.value); - if (X86_REX_B(insn->rex_prefix.value) == 1) + if (X86_REX_B(insn->rex_prefix.value)) regno += 8; break; |