From: Mark Wielaard <mark@klomp.org>
Date: Mon, 16 Apr 2018 14:53:56 +0000 (+0200)
Subject: Don't read build-id ELF Note in .debug file through phdrs.
X-Git-Tag: VALGRIND_3_14_0~122
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1f543a224eec5afd8cfddea70c1307ed0a20c55;p=thirdparty%2Fvalgrind.git

Don't read build-id ELF Note in .debug file through phdrs.

Bug #393062 - Reading build-id ELF note through phdrs triggers
              "debuginfo reader: ensure_valid failed"

Skip the phdrs when we have to search the shdrs. In separate
.debug files the phdrs might not be valid (they are a copy of
the main ELF file) and might trigger assertions when getting
image notes based on them.
---

diff --git a/NEWS b/NEWS
index ce01442d47..95a6196557 100644
--- a/NEWS
+++ b/NEWS
@@ -104,6 +104,7 @@ where XXXXXX is the bug number as listed below.
 393017  Add missing support for xsmaxcdp instruction, bug fixes for xsmincdp,
         lxssp, stxssp and stxvl instructions.
 393023  callgrind_control risks using the wrong vgdb
+393062  build-id ELF phdrs read causes "debuginfo reader: ensure_valid failed"
 393099  posix_memalign() invalid write if alignment == 0
 
 n-i-bz  Fix missing workq_ops operations (macOS)
diff --git a/coregrind/m_debuginfo/readelf.c b/coregrind/m_debuginfo/readelf.c
index 70c28e6292..62192f00e1 100644
--- a/coregrind/m_debuginfo/readelf.c
+++ b/coregrind/m_debuginfo/readelf.c
@@ -1137,7 +1137,11 @@ HChar* find_buildid(DiImage* img, Bool rel_ok, Bool search_shdrs)
 
       ElfXX_Ehdr ehdr;
       ML_(img_get)(&ehdr, img, 0, sizeof(ehdr));
-      for (i = 0; i < ehdr.e_phnum; i++) {
+      /* Skip the phdrs when we have to search the shdrs. In separate
+         .debug files the phdrs might not be valid (they are a copy of
+         the main ELF file) and might trigger assertions when getting
+         image notes based on them. */
+      for (i = 0; !search_shdrs && i < ehdr.e_phnum; i++) {
          ElfXX_Phdr phdr;
          ML_(img_get)(&phdr, img,
                       ehdr.e_phoff + i * ehdr.e_phentsize, sizeof(phdr));