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-rw-r--r--elf/dl-tls.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 7b3dd9a..670dbc4 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -819,7 +819,14 @@ _dl_update_slotinfo (unsigned long int req_modid, size_t new_gen)
dtv entry free it. Note: this is not AS-safe. */
/* XXX Ideally we will at some point create a memory
pool. */
- free (dtv[modid].pointer.to_free);
+ /* Avoid calling free on a null pointer. Some mallocs
+ incorrectly use dynamic TLS, and depending on how the
+ free function was compiled, it could call
+ __tls_get_addr before the null pointer check in the
+ free implementation. Checking here papers over at
+ least some dynamic TLS usage by interposed mallocs. */
+ if (dtv[modid].pointer.to_free != NULL)
+ free (dtv[modid].pointer.to_free);
dtv[modid].pointer.val = TLS_DTV_UNALLOCATED;
dtv[modid].pointer.to_free = NULL;