[PATCH] fix is_at_popf() for compat tasks
When testing for the REX instruction prefix, first check
for 32-bit mode because in compat mode the REX prefix is an
increment instruction.
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index d35ec1b..3a52c7b 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -141,8 +141,11 @@
case 0xf0: case 0xf2: case 0xf3:
continue;
- /* REX prefixes */
case 0x40 ... 0x4f:
+ if (regs->cs != __USER_CS)
+ /* 32-bit mode: register increment */
+ return 0;
+ /* 64-bit mode: REX prefix */
continue;
/* CHECKME: f0, f2, f3 */