From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Rabin Vincent <rabin@rab.in>
Subject: [PATCH 6/6] ftrace: Fix hash record accounting bug
Date: Mon, 05 Dec 2011 20:41:16 -0500 [thread overview]
Message-ID: <20111206014226.557639917@goodmis.org> (raw)
In-Reply-To: 20111206014110.079874115@goodmis.org
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From: Steven Rostedt <srostedt@redhat.com>
If the set_ftrace_filter is cleared by writing just whitespace to
it, then the filter hash refcounts will be decremented but not
updated. This causes two bugs:
1) No functions will be enabled for tracing when they all should be
2) If the users clears the set_ftrace_filter twice, it will crash ftrace:
------------[ cut here ]------------
WARNING: at /home/rostedt/work/git/linux-trace.git/kernel/trace/ftrace.c:1384 __ftrace_hash_rec_update.part.27+0x157/0x1a7()
Modules linked in:
Pid: 2330, comm: bash Not tainted 3.1.0-test+ #32
Call Trace:
[<ffffffff81051828>] warn_slowpath_common+0x83/0x9b
[<ffffffff8105185a>] warn_slowpath_null+0x1a/0x1c
[<ffffffff810ba362>] __ftrace_hash_rec_update.part.27+0x157/0x1a7
[<ffffffff810ba6e8>] ? ftrace_regex_release+0xa7/0x10f
[<ffffffff8111bdfe>] ? kfree+0xe5/0x115
[<ffffffff810ba51e>] ftrace_hash_move+0x2e/0x151
[<ffffffff810ba6fb>] ftrace_regex_release+0xba/0x10f
[<ffffffff8112e49a>] fput+0xfd/0x1c2
[<ffffffff8112b54c>] filp_close+0x6d/0x78
[<ffffffff8113a92d>] sys_dup3+0x197/0x1c1
[<ffffffff8113a9a6>] sys_dup2+0x4f/0x54
[<ffffffff8150cac2>] system_call_fastpath+0x16/0x1b
---[ end trace 77a3a7ee73794a02 ]---
Link: http://lkml.kernel.org/r/20111101141420.GA4918@debian
Reported-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1276b3c..b1e8943 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1211,7 +1211,9 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
if (!src->count) {
free_ftrace_hash_rcu(*dst);
rcu_assign_pointer(*dst, EMPTY_HASH);
- return 0;
+ /* still need to update the function records */
+ ret = 0;
+ goto out;
}
/*
--
1.7.7.3
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next prev parent reply other threads:[~2011-12-06 1:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-06 1:41 [PATCH 0/6] [GIT PULL][v3.2] tracing: fixes Steven Rostedt
2011-12-06 1:41 ` [PATCH 1/6] tracing: fix event_subsystem ref counting Steven Rostedt
2011-12-06 1:41 ` [PATCH 2/6] tracing: Restore system filter behavior Steven Rostedt
2011-12-06 1:41 ` [PATCH 3/6] ftrace: Remove force undef config value left for testing Steven Rostedt
2011-12-06 1:41 ` [PATCH 4/6] jump_label: jump_label_inc may return before the code is patched Steven Rostedt
2011-12-06 1:41 ` [PATCH 5/6] perf: Fix parsing of __print_flags() in TP_printk() Steven Rostedt
2011-12-06 1:41 ` Steven Rostedt [this message]
2011-12-06 5:43 ` [PATCH 0/6] [GIT PULL][v3.2] tracing: fixes Ingo Molnar
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