Revision 321027c1fe77f892f4ea07846aeae08cefbbb290 authored by Peter Zijlstra on 11 January 2017, 20:09:50 UTC, committed by Ingo Molnar on 14 January 2017, 09:56:11 UTC
Di Shen reported a race between two concurrent sys_perf_event_open() calls where both try and move the same pre-existing software group into a hardware context. The problem is exactly that described in commit: f63a8daa5812 ("perf: Fix event->ctx locking") ... where, while we wait for a ctx->mutex acquisition, the event->ctx relation can have changed under us. That very same commit failed to recognise sys_perf_event_context() as an external access vector to the events and thereby didn't apply the established locking rules correctly. So while one sys_perf_event_open() call is stuck waiting on mutex_lock_double(), the other (which owns said locks) moves the group about. So by the time the former sys_perf_event_open() acquires the locks, the context we've acquired is stale (and possibly dead). Apply the established locking rules as per perf_event_ctx_lock_nested() to the mutex_lock_double() for the 'move_group' case. This obviously means we need to validate state after we acquire the locks. Reported-by: Di Shen (Keen Lab) Tested-by: John Dias <joaodias@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Min Chong <mchong@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Fixes: f63a8daa5812 ("perf: Fix event->ctx locking") Link: http://lkml.kernel.org/r/20170106131444.GZ3174@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
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trusted-type.h
/*
* Copyright (C) 2010 IBM Corporation
* Author: David Safford <safford@us.ibm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2 of the License.
*/
#ifndef _KEYS_TRUSTED_TYPE_H
#define _KEYS_TRUSTED_TYPE_H
#include <linux/key.h>
#include <linux/rcupdate.h>
#include <linux/tpm.h>
#define MIN_KEY_SIZE 32
#define MAX_KEY_SIZE 128
#define MAX_BLOB_SIZE 512
#define MAX_PCRINFO_SIZE 64
#define MAX_DIGEST_SIZE 64
struct trusted_key_payload {
struct rcu_head rcu;
unsigned int key_len;
unsigned int blob_len;
unsigned char migratable;
unsigned char key[MAX_KEY_SIZE + 1];
unsigned char blob[MAX_BLOB_SIZE];
};
struct trusted_key_options {
uint16_t keytype;
uint32_t keyhandle;
unsigned char keyauth[TPM_DIGEST_SIZE];
unsigned char blobauth[TPM_DIGEST_SIZE];
uint32_t pcrinfo_len;
unsigned char pcrinfo[MAX_PCRINFO_SIZE];
int pcrlock;
uint32_t hash;
uint32_t policydigest_len;
unsigned char policydigest[MAX_DIGEST_SIZE];
uint32_t policyhandle;
};
extern struct key_type key_type_trusted;
#endif /* _KEYS_TRUSTED_TYPE_H */
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