On Fri, Aug 18, 2017 at 05:27:46PM -0700, Ricardo Neri wrote:
> Even though memory addresses are unsigned, the operands used to compute the
> effective address do have a sign. This is true for ModRM.rm, SIB.base,
> SIB.index as well as the displacement bytes. Thus, signed variables shall
> be used when computing the effective address from these operands. Once the
> signed effective address has been computed, it is casted to an unsigned
> long to determine the linear address.
>
> Variables are renamed to better reflect the type of address being
> computed.
>
> Cc: Borislav Petkov <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Cc: Dave Hansen <[email protected]>
> Cc: Adam Buchbinder <[email protected]>
> Cc: Colin Ian King <[email protected]>
> Cc: Lorenzo Stoakes <[email protected]>
> Cc: Qiaowei Ren <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Nathan Howard <[email protected]>
> Cc: Adan Hawthorn <[email protected]>
> Cc: Joe Perches <[email protected]>
> Cc: Ravi V. Shankar <[email protected]>
> Cc: [email protected]
> Signed-off-by: Ricardo Neri <[email protected]>
> ---
> arch/x86/mm/mpx.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
I think you can simplify this function even more (diff ontop):
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 9eec98022510..d0ec5c9b2a57 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -139,7 +139,7 @@ static int get_reg_offset(struct insn *insn, struct pt_regs
*regs,
static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs)
{
int addr_offset, base_offset, indx_offset;
- unsigned long linear_addr;
+ unsigned long linear_addr = -1;
long eff_addr, base, indx;
insn_byte_t sib;
@@ -150,18 +150,18 @@ static void __user *mpx_get_addr_ref(struct insn *insn,
struct pt_regs *regs)
if (X86_MODRM_MOD(insn->modrm.value) == 3) {
addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM);
if (addr_offset < 0)
- goto out_err;
+ goto out;
eff_addr = regs_get_register(regs, addr_offset);
} else {
if (insn->sib.nbytes) {
base_offset = get_reg_offset(insn, regs, REG_TYPE_BASE);
if (base_offset < 0)
- goto out_err;
+ goto out;
indx_offset = get_reg_offset(insn, regs,
REG_TYPE_INDEX);
if (indx_offset < 0)
- goto out_err;
+ goto out;
base = regs_get_register(regs, base_offset);
indx = regs_get_register(regs, indx_offset);
@@ -170,7 +170,7 @@ static void __user *mpx_get_addr_ref(struct insn *insn,
struct pt_regs *regs)
} else {
addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM);
if (addr_offset < 0)
- goto out_err;
+ goto out;
eff_addr = regs_get_register(regs, addr_offset);
}
@@ -180,9 +180,8 @@ static void __user *mpx_get_addr_ref(struct insn *insn,
struct pt_regs *regs)
linear_addr = (unsigned long)eff_addr;
+out:
return (void __user *)linear_addr;
-out_err:
- return (void __user *)-1;
}
static int mpx_insn_decode(struct insn *insn,
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284
(AG Nürnberg)
--
