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>
1 parent 63cae12
compress.c
/*
* Cryptographic API.
*
* Compression operations.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
*
* 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; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/string.h>
#include "internal.h"
static int crypto_compress(struct crypto_tfm *tfm,
const u8 *src, unsigned int slen,
u8 *dst, unsigned int *dlen)
{
return tfm->__crt_alg->cra_compress.coa_compress(tfm, src, slen, dst,
dlen);
}
static int crypto_decompress(struct crypto_tfm *tfm,
const u8 *src, unsigned int slen,
u8 *dst, unsigned int *dlen)
{
return tfm->__crt_alg->cra_compress.coa_decompress(tfm, src, slen, dst,
dlen);
}
int crypto_init_compress_ops(struct crypto_tfm *tfm)
{
struct compress_tfm *ops = &tfm->crt_compress;
ops->cot_compress = crypto_compress;
ops->cot_decompress = crypto_decompress;
return 0;
}
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