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Work around TLS deallocation via free().

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glibc uses memalign()/free() to allocate/deallocate TLS, which means
that it is unsafe to set TLS variables as a side effect of free() --
they may already be deallocated.  Work around this by avoiding
tcache_create() within free().

Reported by Mike Hommey.
This commit is contained in:
Jason Evans
2012-03-30 12:11:03 -07:00
parent 3c2ba0dcbc
commit 09a0769ba7
2 changed files with 18 additions and 5 deletions
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16
include/jemalloc/internal/tcache.h
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@@ -126,7 +126,7 @@ malloc_tsd_protos(JEMALLOC_ATTR(unused), tcache_enabled, tcache_enabled_t)
void tcache_event(tcache_t *tcache);
void tcache_flush(void);
bool tcache_enabled_get(void);
tcache_t *tcache_get(void);
tcache_t *tcache_get(bool create);
void tcache_enabled_set(bool enabled);
void *tcache_alloc_easy(tcache_bin_t *tbin);
void *tcache_alloc_small(tcache_t *tcache, size_t size, bool zero);
@@ -205,7 +205,7 @@ tcache_enabled_set(bool enabled)
}
JEMALLOC_INLINE tcache_t *
tcache_get(void)
tcache_get(bool create)
{
tcache_t *tcache;
@@ -219,6 +219,18 @@ tcache_get(void)
if (tcache == TCACHE_STATE_DISABLED)
return (NULL);
if (tcache == NULL) {
if (create == false) {
/*
* Creating a tcache here would cause
* allocation as a side effect of free().
* Ordinarily that would be okay since
* tcache_create() failure is a soft failure
* that doesn't propagate. However, if TLS
* data are freed via free() as in glibc,
* subtle TLS corruption could result.
*/
return (NULL);
}
if (tcache_enabled_get() == false) {
tcache_enabled_set(false); /* Memoize. */
return (NULL);