From: Will Deacon <will.deacon@arm.com>
Date: Fri, 27 Jun 2014 16:01:47 +0000 (+0100)
Subject: ARM: 8087/1: ptrace: reload syscall number after secure_computing() check
X-Git-Tag: omap-for-v3.16/fixes-rc4~34^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=42309ab450b608ddcfafa90e4cfa93a5001ecfba;p=pandora-kernel.git

ARM: 8087/1: ptrace: reload syscall number after secure_computing() check

On the syscall tracing path, we call out to secure_computing() to allow
seccomp to check the syscall number being attempted. As part of this, a
SIGTRAP may be sent to the tracer and the syscall could be re-written by
a subsequent SET_SYSCALL ptrace request. Unfortunately, this new syscall
is ignored by the current code unless TIF_SYSCALL_TRACE is also set on
the current thread.

This patch slightly reworks the enter path of the syscall tracing code
so that we always reload the syscall number from
current_thread_info()->syscall after the potential ptrace traps.

Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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