linux-kernel - [PATCH] perf: Fix unincremented buffer base on partial copy

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-next>] [day] [month] [year] [list]

Message-Id: <1274988898-5639-1-git-send-regression-fweisbec@gmail.com>
Date:	Thu, 27 May 2010 21:34:58 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>
Subject: [PATCH] perf: Fix unincremented buffer base on partial copy

If a sample size crosses to the next page boundary, the copy
will be made in more than one step. However we forget to advance
the source offset for the next copy, leading to unexpected double
copies that completely mess up the traces.

This fixes various kinds of bad traces that have irrelevant
datas inside, as an example:

	geany-4979  [001]  5758.077775: sched_switch: prev_comm=! prev_pid=121
		prev_prio=0 prev_state=S|D|Z|X|x ==> next_comm= next_pid=7497072
		next_prio=0

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Paul Mackerras <paulus@...ba.org>
---
 kernel/perf_event.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index e099650..3d82e1a 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2977,6 +2977,7 @@ __always_inline void perf_output_copy(struct perf_output_handle *handle,
 
 		len -= size;
 		handle->addr += size;
+		buf += size;
 		handle->size -= size;
 		if (!handle->size) {
 			struct perf_mmap_data *data = handle->data;
-- 
1.6.2.3

--
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/