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[msan] Fix a data race in signal/sigaction interceptors. 

llvm-svn: 189342
This commit is contained in:
Evgeniy Stepanov 2013-08-27 11:34:05 +00:00
parent a710d810f5
commit bb25af5f7b
1 changed files with 17 additions and 6 deletions
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23
compiler-rt/lib/msan/msan_interceptors.cc
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@ -19,6 +19,7 @@
#include "msan.h"
#include "sanitizer_common/sanitizer_platform_limits_posix.h"
#include "sanitizer_common/sanitizer_allocator.h"
#include "sanitizer_common/sanitizer_atomic.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
#include "sanitizer_common/sanitizer_libc.h"
@ -30,6 +31,11 @@
using namespace __msan;
using __sanitizer::memory_order;
using __sanitizer::atomic_load;
using __sanitizer::atomic_store;
using __sanitizer::atomic_uintptr_t;
// True if this is a nested interceptor.
static THREADLOCAL int in_interceptor_scope;
@ -897,13 +903,17 @@ INTERCEPTOR(int, getrusage, int who, void *usage) {
return res;
}
// sigactions_mu guarantees atomicity of sigaction() and signal() calls.
// Access to sigactions[] is gone with relaxed atomics to avoid data race with
// the signal handler.
const int kMaxSignals = 1024;
static uptr sigactions[kMaxSignals];
static atomic_uintptr_t sigactions[kMaxSignals];
static StaticSpinMutex sigactions_mu;
static void SignalHandler(int signo) {
typedef void (*signal_cb)(int x);
signal_cb cb = (signal_cb)sigactions[signo];
signal_cb cb =
(signal_cb)atomic_load(&sigactions[signo], memory_order_relaxed);
cb(signo);
}
@ -913,7 +923,8 @@ static void SignalAction(int signo, void *si, void *uc) {
__msan_unpoison(uc, __sanitizer::ucontext_t_sz);
typedef void (*sigaction_cb)(int, void *, void *);
sigaction_cb cb = (sigaction_cb)sigactions[signo];
sigaction_cb cb =
(sigaction_cb)atomic_load(&sigactions[signo], memory_order_relaxed);
cb(signo, si, uc);
}
@ -926,7 +937,7 @@ INTERCEPTOR(int, sigaction, int signo, const __sanitizer_sigaction *act,
if (flags()->wrap_signals) {
SpinMutexLock lock(&sigactions_mu);
CHECK_LT(signo, kMaxSignals);
uptr old_cb = sigactions[signo];
uptr old_cb = atomic_load(&sigactions[signo], memory_order_relaxed);
__sanitizer_sigaction new_act;
__sanitizer_sigaction *pnew_act = act ? &new_act : 0;
if (act) {
@ -936,7 +947,7 @@ INTERCEPTOR(int, sigaction, int signo, const __sanitizer_sigaction *act,
? (uptr)SignalAction
: (uptr)SignalHandler;
if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
sigactions[signo] = cb;
atomic_store(&sigactions[signo], cb, memory_order_relaxed);
pnew_act->sa_sigaction = (void (*)(int, void *, void *))new_cb;
}
}
@ -963,7 +974,7 @@ INTERCEPTOR(int, signal, int signo, uptr cb) {
CHECK_LT(signo, kMaxSignals);
SpinMutexLock lock(&sigactions_mu);
if (cb != __sanitizer::sig_ign && cb != __sanitizer::sig_dfl) {
sigactions[signo] = cb;
atomic_store(&sigactions[signo], cb, memory_order_relaxed);
cb = (uptr) SignalHandler;
}
return REAL(signal)(signo, cb);