Commit-ID: 2eece390bf68ec8f733d7e4a3ba8a5ea350082ae
Gitweb: https://git.kernel.org/tip/2eece390bf68ec8f733d7e4a3ba8a5ea350082ae
Author: Alexander Shishkin <[email protected]>
AuthorDate: Mon, 23 Oct 2017 15:35:33 +0300
Committer: Ingo Molnar <[email protected]>
CommitDate: Tue, 24 Oct 2017 13:19:27 +0200
perf/x86/intel/bts: Fix exclusive event reference leak
Commit:
d2878d642a4ed ("perf/x86/intel/bts: Disallow use by unprivileged users on
paranoid systems")
... adds a privilege check in the exactly wrong place in the event init path:
after the 'LBR exclusive' reference has been taken, and doesn't release it
in the case of insufficient privileges. After this, nobody in the system
gets to use PT or LBR afterwards.
This patch moves the privilege check to where it should have been in the
first place.
Signed-off-by: Alexander Shishkin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: d2878d642a4ed ("perf/x86/intel/bts: Disallow use by unprivileged users
on paranoid systems")
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/events/intel/bts.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 16076eb..141e07b 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -546,9 +546,6 @@ static int bts_event_init(struct perf_event *event)
if (event->attr.type != bts_pmu.type)
return -ENOENT;
- if (x86_add_exclusive(x86_lbr_exclusive_bts))
- return -EBUSY;
-
/*
* BTS leaks kernel addresses even when CPL0 tracing is
* disabled, so disallow intel_bts driver for unprivileged
@@ -562,6 +559,9 @@ static int bts_event_init(struct perf_event *event)
!capable(CAP_SYS_ADMIN))
return -EACCES;
+ if (x86_add_exclusive(x86_lbr_exclusive_bts))
+ return -EBUSY;
+
ret = x86_reserve_hardware();
if (ret) {
x86_del_exclusive(x86_lbr_exclusive_bts);
