linux-kernel - [PATCH 06/13] ptrace/x86: simplify the "disable" logic in ptrace_write

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: <20130513151718.GA6266@redhat.com>
Date:	Mon, 13 May 2013 17:17:18 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Jan Kratochvil <jan.kratochvil@...hat.com>,
	Michael Neuling <mikey@...ling.org>,
	Paul Mackerras <paulus@...ba.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	Prasad <prasad@...ux.vnet.ibm.com>,
	Russell King <linux@....linux.org.uk>,
	Will Deacon <will.deacon@....com>, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 06/13] ptrace/x86: simplify the "disable" logic in
	ptrace_write_dr7()

ptrace_write_dr7() looks unnecessarily overcomplicated. We can
factor out ptrace_modify_breakpoint() and do not do "continue"
twice, just we need to pass the proper "disabled" argument to
ptrace_modify_breakpoint().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: Frederic Weisbecker <fweisbec@...il.com>
---
 arch/x86/kernel/ptrace.c |   40 +++++++++++++++-------------------------
 1 files changed, 15 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7a98b21..0649f16 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -637,9 +637,7 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
 	struct thread_struct *thread = &(tsk->thread);
 	unsigned long old_dr7;
 	int i, orig_ret = 0, rc = 0;
-	int enabled, second_pass = 0;
-	unsigned len, type;
-	struct perf_event *bp;
+	int second_pass = 0;
 
 	data &= ~DR_CONTROL_RESERVED;
 	old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
@@ -649,30 +647,22 @@ restore:
 	 * appropriate changes to each.
 	 */
 	for (i = 0; i < HBP_NUM; i++) {
-		enabled = decode_dr7(data, i, &len, &type);
-		bp = thread->ptrace_bps[i];
-
-		if (!enabled) {
-			if (bp) {
-				/*
-				 * Don't unregister the breakpoints right-away,
-				 * unless all register_user_hw_breakpoint()
-				 * requests have succeeded. This prevents
-				 * any window of opportunity for debug
-				 * register grabbing by other users.
-				 */
-				if (!second_pass)
-					continue;
-
-				rc = ptrace_modify_breakpoint(bp, len, type,
-							      tsk, 1);
-				if (rc)
-					break;
-			}
-			continue;
+		unsigned len, type;
+		bool disabled = !decode_dr7(data, i, &len, &type);
+		struct perf_event *bp = thread->ptrace_bps[i];
+
+		if (disabled) {
+			/*
+			 * Don't unregister the breakpoints right-away, unless
+			 * all register_user_hw_breakpoint() requests have
+			 * succeeded. This prevents any window of opportunity
+			 * for debug register grabbing by other users.
+			 */
+			if (!bp || !second_pass)
+				continue;
 		}
 
-		rc = ptrace_modify_breakpoint(bp, len, type, tsk, 0);
+		rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
 		if (rc)
 			break;
 	}
-- 
1.5.5.1

--
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/