The segment register high words on x86_32 may contain garbage. Teach regs_get_register() to read them as u16 instead of unsigned long.
Cc: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Andy Lutomirski <l...@kernel.org> --- arch/x86/include/asm/ptrace.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index 2d3681083307..ca6cded447f5 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -196,6 +196,17 @@ static inline unsigned long regs_get_register(struct pt_regs *regs, if (offset == offsetof(struct pt_regs, sp) && regs->cs == __KERNEL_CS) return kernel_stack_pointer(regs); + + /* The selector fields are 16-bit. */ + if (offset == offsetof(struct pt_regs, cs) || + offset == offsetof(struct pt_regs, ss) || + offset == offsetof(struct pt_regs, ds) || + offset == offsetof(struct pt_regs, es) || + offset == offsetof(struct pt_regs, fs) || + offset == offsetof(struct pt_regs, gs)) { + return *(u16 *)((unsigned long)regs + offset); + + } #endif return *(unsigned long *)((unsigned long)regs + offset); } -- 2.13.3