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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-10-23 15:35:33 +0300
committerIngo Molnar <mingo@kernel.org>2017-10-24 14:19:27 +0300
commit2eece390bf68ec8f733d7e4a3ba8a5ea350082ae (patch)
tree94e5167d90a56e6437789583a626ca34a090b27b /arch/x86/events
parent6cff0a118f23b98c604a3604ea9de11338e24fbe (diff)
downloadlinux-2eece390bf68ec8f733d7e4a3ba8a5ea350082ae.tar.xz
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 <alexander.shishkin@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d2878d642a4ed ("perf/x86/intel/bts: Disallow use by unprivileged users on paranoid systems") Link: http://lkml.kernel.org/r/20171023123533.16973-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/events')
-rw-r--r--arch/x86/events/intel/bts.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 16076eb34699..141e07b06216 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);