[PATCH 7/7] Add sanity checks to ld.so DSBT support

Bernd Schmidt bernds_cb1 at t-online.de
Wed Mar 2 20:21:57 UTC 2011


From: Mark Salter <msalter at redhat.com>

This adds some DSBT index sanity checks to the runtime linker. It
catches libraries which have no index (index 0) and libraries which
try to use an already used index.

Signed-off-by: Bernd Schmidt <bernds at codesourcery.com>
---
 ldso/ldso/dl-elf.c |   29 ++++++++++++++++++++++++++++-
 1 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c
index 7227bfd..0efe7c7 100644
--- a/ldso/ldso/dl-elf.c
+++ b/ldso/ldso/dl-elf.c
@@ -813,13 +813,40 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
 		int idx = tpnt->loadaddr.map->dsbt_index;
 		unsigned *dsbt = tpnt->loadaddr.map->dsbt_table;
 
+		if (idx == 0) {
+			/* This DSO has not been assigned an index */
+			_dl_dprintf(2, "%s: '%s' is missing a dsbt index assignment!\n",
+				    _dl_progname, libname);
+			_dl_exit(1);
+		}
+
 		/*
 		 * Setup dsbt slot for this module in dsbt of all modules.
 		 */
 		for (t = _dl_loaded_modules; t; t = t->next) {
 			/* find a dsbt table from another module */
-			if (ref == NULL && t != tpnt)
+			if (ref == NULL && t != tpnt) {
 				ref = t;
+
+				/* make sure index is not already used */
+				if (t->loadaddr.map->dsbt_table[idx]) {
+					struct elf_resolve *dup;
+					char *dup_name;
+
+					for (dup = _dl_loaded_modules; dup; dup = dup->next)
+						if (dup != tpnt && dup->loadaddr.map->dsbt_index == idx)
+							break;
+					if (dup)
+						dup_name = dup->libname;
+					else if (idx == 1)
+						dup_name = "runtime linker";
+					else
+						dup_name = "unknown library";
+					_dl_dprintf(2, "%s: '%s' dsbt index %d already used by %s!\n",
+						    _dl_progname, libname, idx, dup_name);
+					_dl_exit(1);
+				}
+			}
 			t->loadaddr.map->dsbt_table[idx] = (unsigned)dsbt;
 		}
 		if (ref)
-- 
1.7.3.4



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