Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750902Ab3CAFpq (ORCPT ); Fri, 1 Mar 2013 00:45:46 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:53406 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750696Ab3CAFpp (ORCPT ); Fri, 1 Mar 2013 00:45:45 -0500 Date: Fri, 1 Mar 2013 11:15:36 +0530 From: Ananth N Mavinakayanahalli To: Anton Arapov Cc: Oleg Nesterov , Srikar Dronamraju , LKML , Josh Stone , Frank Eigler , Peter Zijlstra , Ingo Molnar Subject: Re: [RFC PATCH v3 2/6] uretprobes/x86: hijack return address Message-ID: <20130301054536.GB30500@in.ibm.com> Reply-To: ananth@in.ibm.com References: <1362049215-5780-1-git-send-email-anton@redhat.com> <1362049215-5780-3-git-send-email-anton@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1362049215-5780-3-git-send-email-anton@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13030105-2876-0000-0000-000005D8EBE9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2167 Lines: 51 On Thu, Feb 28, 2013 at 12:00:11PM +0100, Anton Arapov wrote: > hijack the return address and replace it with a "trampoline" > > v2: > - remove ->doomed flag, kill task immediately > > Signed-off-by: Anton Arapov > --- > arch/x86/include/asm/uprobes.h | 1 + > arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++ > 2 files changed, 30 insertions(+) > > diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h > index 8ff8be7..c353555 100644 > --- a/arch/x86/include/asm/uprobes.h > +++ b/arch/x86/include/asm/uprobes.h > @@ -55,4 +55,5 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs); > extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); > extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); > extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); > +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long rp_trampoline_vaddr, struct pt_regs *regs); > #endif /* _ASM_UPROBES_H */ > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > index 0ba4cfb..85e2153 100644 > --- a/arch/x86/kernel/uprobes.c > +++ b/arch/x86/kernel/uprobes.c > @@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) > send_sig(SIGTRAP, current, 0); > return ret; > } > + > +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long > + rp_trampoline_vaddr, struct pt_regs *regs) > +{ > + int rasize, ncopied; > + unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */ > + > + rasize = is_ia32_task() ? 4 : 8; > + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize); > + if (unlikely(ncopied)) What if ncopied < rasize? Agreed that the upper order bits can be 0, but should you not validate ncopied == rasize? Ananth -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/