52 lines
1.9 KiB
Diff
52 lines
1.9 KiB
Diff
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From: Steven Rostedt <srostedt@redhat.com>
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Date: Wed, 8 Sep 2010 15:20:37 +0000 (-0400)
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Subject: tracing: Do not allow llseek to set_ftrace_filter
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=9c55cb12c1c172e2d51e85fbb5a4796ca86b77e7
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tracing: Do not allow llseek to set_ftrace_filter
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Reading the file set_ftrace_filter does three things.
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1) shows whether or not filters are set for the function tracer
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2) shows what functions are set for the function tracer
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3) shows what triggers are set on any functions
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3 is independent from 1 and 2.
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The way this file currently works is that it is a state machine,
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and as you read it, it may change state. But this assumption breaks
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when you use lseek() on the file. The state machine gets out of sync
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and the t_show() may use the wrong pointer and cause a kernel oops.
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Luckily, this will only kill the app that does the lseek, but the app
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dies while holding a mutex. This prevents anyone else from using the
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set_ftrace_filter file (or any other function tracing file for that matter).
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A real fix for this is to rewrite the code, but that is too much for
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a -rc release or stable. This patch simply disables llseek on the
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set_ftrace_filter() file for now, and we can do the proper fix for the
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next major release.
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Reported-by: Robert Swiecki <swiecki@google.com>
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Cc: Chris Wright <chrisw@sous-sol.org>
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Cc: Tavis Ormandy <taviso@google.com>
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Cc: Eugene Teo <eugene@redhat.com>
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Cc: vendor-sec@lst.de
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Cc: <stable@kernel.org>
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Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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---
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diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
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index 7cb1f45..83a16e9 100644
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--- a/kernel/trace/ftrace.c
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+++ b/kernel/trace/ftrace.c
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@@ -2416,7 +2416,7 @@ static const struct file_operations ftrace_filter_fops = {
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.open = ftrace_filter_open,
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.read = seq_read,
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.write = ftrace_filter_write,
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- .llseek = ftrace_regex_lseek,
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+ .llseek = no_llseek,
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.release = ftrace_filter_release,
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};
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