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authorSteven Rostedt <srostedt@redhat.com>2010-09-08 11:20:37 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-09-08 12:08:01 -0400
commit9c55cb12c1c172e2d51e85fbb5a4796ca86b77e7 (patch)
tree0f86d1e27fbfc31cba108e71643d686315468db9
parent4177c42a6301a34c20038ec2771a33dcc30bb338 (diff)
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tracing: Do not allow llseek to set_ftrace_filter
Reading the file set_ftrace_filter does three things. 1) shows whether or not filters are set for the function tracer 2) shows what functions are set for the function tracer 3) shows what triggers are set on any functions 3 is independent from 1 and 2. The way this file currently works is that it is a state machine, and as you read it, it may change state. But this assumption breaks when you use lseek() on the file. The state machine gets out of sync and the t_show() may use the wrong pointer and cause a kernel oops. Luckily, this will only kill the app that does the lseek, but the app dies while holding a mutex. This prevents anyone else from using the set_ftrace_filter file (or any other function tracing file for that matter). A real fix for this is to rewrite the code, but that is too much for a -rc release or stable. This patch simply disables llseek on the set_ftrace_filter() file for now, and we can do the proper fix for the next major release. Reported-by: Robert Swiecki <swiecki@google.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Tavis Ormandy <taviso@google.com> Cc: Eugene Teo <eugene@redhat.com> Cc: vendor-sec@lst.de Cc: <stable@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/ftrace.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7cb1f45a1de..83a16e9ee51 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2416,7 +2416,7 @@ static const struct file_operations ftrace_filter_fops = {
.open = ftrace_filter_open,
.read = seq_read,
.write = ftrace_filter_write,
- .llseek = ftrace_regex_lseek,
+ .llseek = no_llseek,
.release = ftrace_filter_release,
};