[2.25 COMMITTED] elf: do not substitute dst in $LD_LIBRARY_PATH twice [BZ #22627]

[2.25 COMMITTED] elf: do not substitute dst in $LD_LIBRARY_PATH twice [BZ #22627]

[Dmitry V. Levin]

Starting with commit
glibc-2.18.90-470-g2a939a7e6d81f109d49306bc2e10b4ac9ceed8f9 that
introduced substitution of dynamic string tokens in fillin_rpath,
_dl_init_paths invokes _dl_dst_substitute for $LD_LIBRARY_PATH twice:
the first time it's called directly, the second time the result
is passed on to fillin_rpath which calls expand_dynamic_string_token
which in turn calls _dl_dst_substitute, leading to the following
behaviour:

$ mkdir -p /tmp/'$ORIGIN' && cd /tmp/'$ORIGIN' &&
  echo 'int main(){}' |gcc -xc - &&
  strace -qq -E LD_LIBRARY_PATH='$ORIGIN' -e /open ./a.out
open("/tmp//tmp/$ORIGIN/tls/x86_64/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/tmp//tmp/$ORIGIN/tls/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/tmp//tmp/$ORIGIN/x86_64/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/tmp//tmp/$ORIGIN/libc.so.6", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3

Fix this by removing the direct _dl_dst_substitute invocation.

* elf/dl-load.c (_dl_init_paths): Remove _dl_dst_substitute preparatory
code and invocation.

(cherry picked from commit bb195224acc14724e9fc2dbaa8d0b20b72ace79b)
---
 ChangeLog     |  6 ++++++
 NEWS          |  1 +
 elf/dl-load.c | 20 +-------------------
 3 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1868c7a..6677169 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-12-18  Dmitry V. Levin  <ldv@altlinux.org>
+
+	[BZ #22627]
+	* elf/dl-load.c (_dl_init_paths): Remove _dl_dst_substitute preparatory
+	code and invocation.
+
 2017-12-14  Florian Weimer  <fweimer@redhat.com>
 
 	[BZ #22607]
diff --git a/NEWS b/NEWS
index 2c4c9d6..7289adb 100644
--- a/NEWS
+++ b/NEWS
@@ -53,6 +53,7 @@ The following bugs are resolved with this release:
   [21778] Robust mutex may deadlock
   [21972] assert macro requires operator== (int) for its argument type
   [22322] libc: [mips64] wrong bits/long-double.h installed
+  [22627] $ORIGIN in $LD_LIBRARY_PATH is substituted twice
 \f
 Version 2.25
 
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 92303b0..ec8cefb 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -776,25 +776,7 @@ _dl_init_paths (const char *llp)
 
   if (llp != NULL && *llp != '\0')
     {
-      char *llp_tmp;
-
-#ifdef SHARED
-      /* Expand DSTs.  */
-      size_t cnt = DL_DST_COUNT (llp, 1);
-      if (__glibc_likely (cnt == 0))
-	llp_tmp = strdupa (llp);
-      else
-	{
-	  /* Determine the length of the substituted string.  */
-	  size_t total = DL_DST_REQUIRED (l, llp, strlen (llp), cnt);
-
-	  /* Allocate the necessary memory.  */
-	  llp_tmp = (char *) alloca (total + 1);
-	  llp_tmp = _dl_dst_substitute (l, llp, llp_tmp, 1);
-	}
-#else
-      llp_tmp = strdupa (llp);
-#endif
+      char *llp_tmp = strdupa (llp);
 
       /* Decompose the LD_LIBRARY_PATH contents.  First determine how many
 	 elements it has.  */
-- 
ldv