MIPS: Guard against any partial write attempt with PTRACE_SETREGSET
authorMaciej W. Rozycki <macro@mips.com>
Mon, 11 Dec 2017 22:52:15 +0000 (22:52 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 17 Jan 2018 08:45:18 +0000 (09:45 +0100)
commita38f387c48c3b364c927e9d983b116824820ed38
treec7ea22be0d00488a7ea00f68d20bea1637cf210c
parentbc511ace4e306b0b0451a6169efe3f5e85d9d6c4
MIPS: Guard against any partial write attempt with PTRACE_SETREGSET

commit dc24d0edf33c3e15099688b6bbdf7bdc24bf6e91 upstream.

Complement commit d614fd58a283 ("mips/ptrace: Preserve previous
registers for short regset write") and ensure that no partial register
write attempt is made with PTRACE_SETREGSET, as we do not preinitialize
any temporaries used to hold incoming register data and consequently
random data could be written.

It is the responsibility of the caller, such as `ptrace_regset', to
arrange for writes to span whole registers only, so here we only assert
that it has indeed happened.

Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Fixes: 72b22bbad1e7 ("MIPS: Don't assume 64-bit FP registers for FP regset")
Cc: James Hogan <james.hogan@mips.com>
Cc: Paul Burton <Paul.Burton@mips.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17926/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/mips/kernel/ptrace.c