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Subject[42/85] perf: Disable monitoring on setuid processes for regular users
3.2.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Stephane Eranian <eranian@google.com>

commit 2976b10f05bd7f6dab9f9e7524451ddfed656a89 upstream.

There was a a bug in setup_new_exec(), whereby
the test to disabled perf monitoring was not
correct because the new credentials for the
process were not yet committed and therefore
the get_dumpable() test was never firing.

The patch fixes the problem by moving the
perf_event test until after the credentials
are committed.

Signed-off-by: Stephane Eranian <eranian@google.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/exec.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1159,13 +1159,6 @@ void setup_new_exec(struct linux_binprm
set_dumpable(current->mm, suid_dumpable);
}

- /*
- * Flush performance counters when crossing a
- * security domain:
- */
- if (!get_dumpable(current->mm))
- perf_event_exit_task(current);
-
/* An exec changes our domain. We are no longer part of the thread
group */

@@ -1229,6 +1222,15 @@ void install_exec_creds(struct linux_bin

commit_creds(bprm->cred);
bprm->cred = NULL;
+
+ /*
+ * Disable monitoring for regular users
+ * when executing setuid binaries. Must
+ * wait until new credentials are committed
+ * by commit_creds() above
+ */
+ if (get_dumpable(current->mm) != SUID_DUMP_USER)
+ perf_event_exit_task(current);
/*
* cred_guard_mutex must be held at least to this point to prevent
* ptrace_attach() from altering our determination of the task's


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