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GNU C Library master sources branch roland/dl-nns created. glibc-2.21-275-g2bd2cad
- From: roland at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 17 Apr 2015 21:30:08 -0000
- Subject: GNU C Library master sources branch roland/dl-nns created. glibc-2.21-275-g2bd2cad
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The branch, roland/dl-nns has been created
at 2bd2cad9e8a410643e80efa0b15f6f2882e1271b (commit)
- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=2bd2cad9e8a410643e80efa0b15f6f2882e1271b
commit 2bd2cad9e8a410643e80efa0b15f6f2882e1271b
Author: Roland McGrath <roland@hack.frob.com>
Date: Fri Apr 17 14:29:40 2015 -0700
Avoid confusing compiler with dynamically impossible statically invalid dereference in _dl_close_worker.
diff --git a/ChangeLog b/ChangeLog
index 967a8c8..0b648bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
2015-04-17 Roland McGrath <roland@hack.frob.com>
+ * elf/dl-close.c (_dl_close_worker) [DL_NNS == 1]: Just assert that
+ IMAP->l_prev cannot be null, and #if out the code for the contrary
+ case, avoiding 'assert (nsid != LM_ID_BASE)' making the compiler
+ believe that NS (&_dl_ns[NSID]) could point outside the array.
+
* elf/dl-open.c (_dl_open): Use __glibc_unlikely in invalid namespace
check. Reject NSID < 0 and NSID >= dl_nns, and check for DL_NNS==1,
before using NSID as an index.
diff --git a/elf/dl-close.c b/elf/dl-close.c
index cf8f9e0..412f71d 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -641,9 +641,16 @@ _dl_close_worker (struct link_map *map)
DL_UNMAP (imap);
/* Finally, unlink the data structure and free it. */
- if (imap->l_prev != NULL)
- imap->l_prev->l_next = imap->l_next;
- else
+#if DL_NNS == 1
+ /* The assert in the (imap->l_prev == NULL) case gives
+ the compiler license to warn that NS points outside
+ the dl_ns array bounds in that case (as nsid != LM_ID_BASE
+ is tantamount to nsid >= DL_NNS). That should be impossible
+ in this configuration, so just assert about it instead. */
+ assert (nsid == LM_ID_BASE);
+ assert (imap->l_prev != NULL);
+#else
+ if (imap->l_prev == NULL)
{
assert (nsid != LM_ID_BASE);
ns->_ns_loaded = imap->l_next;
@@ -652,6 +659,9 @@ _dl_close_worker (struct link_map *map)
we leave for debuggers to examine. */
r->r_map = (void *) ns->_ns_loaded;
}
+ else
+#endif
+ imap->l_prev->l_next = imap->l_next;
--ns->_ns_nloaded;
if (imap->l_next != NULL)
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