Resize segment mapping rewritten sections if needed

NixOS · Apr 23, 2023 · d08bb38 · d08bb38
1 parent 6e7b82e
commit d08bb38
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Showing 4 changed files with 45 additions and 1 deletion.
diff --git a/src/patchelf.cc b/src/patchelf.cc
@@ -1030,6 +1030,18 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsExecutable()
 
         firstPage -= neededPages * getPageSize();
         startOffset += neededPages * getPageSize();
+    } else {
+        Elf_Off rewrittenSectionsOffset = sizeof(Elf_Ehdr) + phdrs.size() * sizeof(Elf_Phdr);
+        for (auto& phdr : phdrs)
+            if (rdi(phdr.p_type) == PT_LOAD &&
+                rdi(phdr.p_offset) <= rewrittenSectionsOffset &&
+                rdi(phdr.p_offset) + rdi(phdr.p_filesz) > rewrittenSectionsOffset &&
+                rdi(phdr.p_filesz) < neededSpace)
+            {
+                wri(phdr.p_filesz, neededSpace);
+                wri(phdr.p_memsz, neededSpace);
+                break;
+            }
     }
 
 

diff --git a/tests/Makefile.am b/tests/Makefile.am
@@ -50,6 +50,7 @@ src_TESTS = \
   rename-dynamic-symbols.sh \
   overlapping-segments-after-rounding.sh \
   shared-rpath.sh \
+  short-first-segment.sh \
   empty-note.sh
 
 build_TESTS = \
@@ -58,7 +59,7 @@ build_TESTS = \
 TESTS = $(src_TESTS) $(build_TESTS)
 
 EXTRA_DIST = no-rpath-prebuild $(src_TESTS) no-rpath-prebuild.sh invalid-elf endianness empty-note \
-			 overlapping-segments-after-rounding
+			 overlapping-segments-after-rounding short-first-segment.zip
 
 TESTS_ENVIRONMENT = PATCHELF_DEBUG=1 STRIP=$(STRIP) OBJDUMP=$(OBJDUMP) READELF=$(READELF) OBJCOPY=$(OBJCOPY)
 

diff --git a/tests/short-first-segment.gz b/tests/short-first-segment.gz
diff --git a/tests/short-first-segment.sh b/tests/short-first-segment.sh
@@ -0,0 +1,31 @@
+#! /bin/sh -e
+
+PATCHELF=$(readlink -f "../src/patchelf")
+SCRATCH="scratch/$(basename "$0" .sh)"
+READELF=${READELF:-readelf}
+
+EXEC_NAME="short-first-segment"
+
+if ! gzip --version >/dev/null; then
+    echo "skipping test: gzip not found"
+    exit 77
+fi
+
+if test "$(uname -i)" = x86_64 && test "$(uname)" = Linux; then
+    echo "skipping test: not supported on x86_64 Linux"
+    exit 77
+fi
+
+rm -rf "${SCRATCH}"
+mkdir -p "${SCRATCH}"
+
+gzip -c -d "${srcdir:?}/${EXEC_NAME}.gz" > "${SCRATCH}/${EXEC_NAME}"
+cd "${SCRATCH}"
+
+ldd "${EXEC_NAME}"
+
+${PATCHELF} --add-rpath lalalalalalalala --output modified1 "${EXEC_NAME}"
+ldd modified1
+
+${PATCHELF}  --add-needed "libXcursor.so.1" --output modified2 modified1
+ldd modified2