x86/dumpstack: Don't dump kernel memory based on usermode RIP

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show_opcodes() is used both for dumping kernel instructions and for dumping
user instructions. If userspace causes #PF by jumping to a kernel address,
show_opcodes() can be reached with regs->ip controlled by the user,
pointing to kernel code. Make sure that userspace can't trick us into
dumping kernel memory into dmesg.

Fixes: 7cccf0725c ("x86/dumpstack: Add a show_ip() function")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: security@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180828154901.112726-1-jannh@google.com

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Jann Horn 2018-08-28 17:49:01 +02:00 • committed by Thomas Gleixner

parent 26e609eccd

commit 342db04ae7

3 changed files with 15 additions and 5 deletions

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2

arch/x86/include/asm/stacktrace.h

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16

arch/x86/kernel/dumpstack.c

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2

arch/x86/mm/fault.c

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