When decoding a user instruction, the bitness depends on CS, not on
TIF_IA32.
Signed-off-by: Andy Lutomirski <l...@amacapital.net>
---
arch/x86/include/asm/ptrace.h | 5 +++++
arch/x86/mm/mpx.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 86fc2bb82287..189113c74726 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -144,6 +144,11 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
(test_thread_flag(TIF_IA32) \
? current_pt_regs()->sp \
: this_cpu_read(old_rsp))
+#else
+static inline bool user_64bit_mode(struct pt_regs *regs)
+{
+ return false;
+}
#endif
#ifdef CONFIG_X86_32
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 67ebf5751222..082ab9c4ac1c 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -217,7 +217,7 @@ static int mpx_insn_decode(struct insn *insn,
struct pt_regs *regs)
{
unsigned char buf[MAX_INSN_SIZE];
- int x86_64 = !test_thread_flag(TIF_IA32);
+ int x86_64 = user_64bit_mode(regs);
int not_copied;
int nr_copied;
--
2.1.0
--
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