Commit bad1a753 authored May 21, 2012 by H.J. Lu Committed by H. Peter Anvin Jun 01, 2012

x86, x32, ptrace: Remove PTRACE_ARCH_PRCTL for x32

When I added x32 ptrace to 3.4 kernel, I also include PTRACE_ARCH_PRCTL
support for x32 GDB  For ARCH_GET_FS/GS, it takes a pointer to int64.  But
at user level, ARCH_GET_FS/GS takes a pointer to int32.  So I have to add
x32 ptrace to glibc to handle it with a temporary int64 passed to kernel and
copy it back to GDB as int32.  Roland suggested that PTRACE_ARCH_PRCTL
is obsolete and x32 GDB should use fs_base and gs_base fields of
user_regs_struct instead.

Accordingly, remove PTRACE_ARCH_PRCTL completely from the x32 code to
avoid possible memory overrun when pointer to int32 is passed to
kernel.

Link: http://lkml.kernel.org/r/CAMe9rOpDzHfS7NH7m1vmD9QRw8SSj4Sc%2BaNOgcWm_WJME2eRsQ@mail.gmail.com


Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org> v3.4

parent 0c759662

arch/x86/kernel/ptrace.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -1211,12 +1211,6 @@ static long x32_arch_ptrace(struct task_struct *child,
		0, sizeof(struct user_i387_struct),
		datap);

		/* normal 64bit interface to access TLS data.
		Works just like arch_prctl, except that the arguments
		are reversed. */
		case PTRACE_ARCH_PRCTL:
		return do_arch_prctl(child, data, addr);

		default:
		return compat_ptrace_request(child, request, addr, data);
		}

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