linux-kernel - [PATCH 3/5] powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1303478187-2367-1-git-send-email-fweisbec@gmail.com>
Date:	Fri, 22 Apr 2011 15:16:27 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	LPPC <linuxppc-dev@...ts.ozlabs.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Will Deacon <will.deacon@....com>,
	Prasad <prasad@...ux.vnet.ibm.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	"v2.6.33.." <stable@...nel.org>
Subject: [PATCH 3/5] powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints

(resend with ppc list in cc)

While the tracer accesses ptrace breakpoints, the child task may
concurrently exit due to a SIGKILL and thus release its breakpoints
at the same time. We can then dereference some freed pointers.

To fix this, hold a reference on the child breakpoints before
manipulating them.

Reported-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Will Deacon <will.deacon@....com>
Cc: Prasad <prasad@...ux.vnet.ibm.com>
Cc: Paul Mundt <lethal@...ux-sh.org>
Cc: v2.6.33.. <stable@...nel.org>
---
 arch/powerpc/kernel/ptrace.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 55613e3..4edeeb3 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long request,
 	}
 
 	case PTRACE_SET_DEBUGREG:
+		if (ptrace_get_breakpoints(child) < 0)
+			return -ESRCH;
 		ret = ptrace_set_debugreg(child, addr, data);
+		ptrace_put_breakpoints(child);
 		break;
 
 #ifdef CONFIG_PPC64
-- 
1.7.3.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/