Update DT_VERDEF when .gnu.version_d is relocated

src/patchelf.cc

@@ -1376,6 +1376,8 @@ void ElfFile<ElfFileParamNames>::rewriteHeaders(Elf_Addr phdrAddress)
             }
             else if (d_tag == DT_VERNEED)
                 dyn->d_un.d_ptr = findSectionHeader(".gnu.version_r").sh_addr;
+            else if (d_tag == DT_VERDEF)
+                dyn->d_un.d_ptr = findSectionHeader(".gnu.version_d").sh_addr;
             else if (d_tag == DT_VERSYM)
                 dyn->d_un.d_ptr = findSectionHeader(".gnu.version").sh_addr;
             /* DT_{PREINIT,INIT,FINI}_ARRAY point at the corresponding

tests/Makefile.am

@@ -64,6 +64,7 @@ src_TESTS = \
   empty-note.sh \
   set-interpreter-same.sh \
   property-rewrite.sh \
+  verdef-relocate.sh \
   large-page-dynamic.sh
 
 build_TESTS = \

tests/verdef-relocate.sh

@@ -0,0 +1,100 @@
+#! /bin/sh -e
+# Regression test: DT_VERDEF must follow .gnu.version_d when it is relocated.
+#
+# rewriteHeaders() updates DT_VERSYM and DT_VERNEED after moving sections but
+# used to leave DT_VERDEF at the pre-relocation address. glibc then walks a
+# stale verdef chain in _dl_check_map_versions and the process can die before
+# main(). See https://github.com/NixOS/patchelf/issues/664.
+#
+# Reproducing needs an object that DEFINES symbol versions (so it has
+# .gnu.version_d at all) and a layout in which patchelf has to move that
+# section. The existing tests only ever patch objects that merely *require*
+# versions, i.e. .gnu.version_r, which was already handled.
+#
+# Whether .gnu.version_d ends up in the way is a property of the linker's
+# section ordering, not of its name, so probe for the layout rather than
+# hardcoding a linker: lld puts .dynstr after the .gnu.version* sections,
+# GNU ld and gold put it before. If no available linker produces a build
+# where the section actually moves, there is nothing to assert: skip.
+
+PATCHELF=${PATCHELF:-../src/patchelf}
+READELF=${READELF:-readelf}
+CC=${CC:-cc}
+
+SCRATCH=scratch/$(basename "$0" .sh)
+rm -rf "${SCRATCH}"
+mkdir -p "${SCRATCH}"
+
+cat > "${SCRATCH}/vexe.c" <<'EOF'
+#include <stdio.h>
+int exported_api(void) { return 42; }
+int main(void) { printf("%d", exported_api()); return 0; }
+EOF
+
+cat > "${SCRATCH}/vexe.map" <<'EOF'
+MYAPP_1.0 { global: exported_api; local: *; };
+EOF
+
+# Long enough that the rpath cannot be edited in place: .dynstr grows, the
+# dynamic cluster is relocated, and .gnu.version_d is evicted with it.
+LONG=$(printf '%0200d' 0 | tr 0 r)
+
+# readelf pads the section address but not the dynamic tag value, so these
+# are compared with $(( )) arithmetic, never as strings.  In `-SW` output the
+# "[ 5]" index splits into two fields while "[12]" does not, so the name is
+# located by scanning rather than by a fixed column.
+verdef_tag() {  # -> DT_VERDEF value, empty if absent
+    ${READELF} -dW "$1" | awk '$2 == "(VERDEF)" { print $3 }'
+}
+verdef_addr() { # -> .gnu.version_d sh_addr, empty if absent
+    ${READELF} -SW "$1" | awk '
+        { for (i = 1; i < NF; i++) if ($i == ".gnu.version_d") { print "0x"$(i+2); exit } }'
+}
+
+found=
+for ld in default lld mold bfd gold; do
+    ldflag=
+    if [ "$ld" != default ]; then
+        ldflag=-fuse-ld=$ld
+        echo 'int main(void){return 0;}' \
+            | ${CC} "$ldflag" -xc - -o "${SCRATCH}/ldprobe" 2>/dev/null || continue
+    fi
+
+    exe="${SCRATCH}/vexe-$ld"
+    # -rdynamic + a version script is what gives an EXECUTABLE its own
+    # .gnu.version_d; non-PIE selects the rewriteSectionsExecutable() path.
+    # shellcheck disable=SC2086 # $ldflag is one optional word, not a path
+    ${CC} -O0 -no-pie -fno-pie $ldflag -rdynamic \
+        -Wl,--version-script="${SCRATCH}/vexe.map" \
+        -o "$exe" "${SCRATCH}/vexe.c" 2>/dev/null || continue
+
+    before=$(verdef_addr "$exe")
+    [ -n "$before" ] || continue
+    [ "$(./"$exe")" = 42 ] || continue
+
+    ${PATCHELF} --set-rpath "/lib/$LONG" "$exe"
+
+    after=$(verdef_addr "$exe")
+    if [ "$((before))" = "$((after))" ]; then
+        echo "linker '$ld': .gnu.version_d not relocated, nothing to check"
+        continue
+    fi
+
+    found=$ld
+    tag=$(verdef_tag "$exe")
+    echo "linker '$ld': .gnu.version_d $before -> $after, DT_VERDEF $tag"
+    if [ -z "$tag" ] || [ "$((tag))" != "$((after))" ]; then
+        echo "FAIL: DT_VERDEF is '$tag' but .gnu.version_d moved to $after"
+        exit 1
+    fi
+
+    # Stale verdef chains do not always crash, so the tag comparison above is
+    # the real oracle; still, the binary must keep working.
+    out=$(./"$exe") || { echo "FAIL: patched binary did not run"; exit 1; }
+    [ "$out" = 42 ] || { echo "FAIL: patched binary printed '$out', want 42"; exit 1; }
+done
+
+if [ -z "$found" ]; then
+    echo "no available linker relocates .gnu.version_d here; skipping"
+    exit 77
+fi