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Date: Wed, 9 Aug 2017 14:39:45 -0700
From: Andy Lutomirski <luto@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH] x86/asm/32: Fix regs_get_register() on segment registers
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 <rostedt@...dmis.org>
Signed-off-by: Andy Lutomirski <luto@...nel.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
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