Fix checking for subdirs when parsing apks

This fixes the check for subdirectories in lib paths. The old check
caused a crash.

Test: Automated
Fixes: 268582810
Change-Id: I520f1fd6772b11821e7c5c97bd51b45b603f5a7b

2 files changed, 8 insertions, 4 deletions

diff --git a/libs/androidfw/ApkParsing.cpp b/libs/androidfw/ApkParsing.cpp
index cf4fbb9b8462..32d2c5b05acb 100644
--- a/libs/androidfw/ApkParsing.cpp
+++ b/libs/androidfw/ApkParsing.cpp
@@ -56,10 +56,8 @@ const char* ValidLibraryPathLastSlash(const char* fileName, bool suppress64Bit,
         return nullptr;
     }
 
-    // Make sure there aren't subdirectories
-    const char* abiOffset = fileName + APK_LIB_LEN;
-    const size_t abiSize = lastSlash - abiOffset;
-    if (memchr(abiOffset, '/', abiSize)) {
+    // Make sure there aren't subdirectories by checking if the next / after lib/ is the last slash
+    if (memchr(fileName + APK_LIB_LEN, '/', fileNameLen - APK_LIB_LEN) != lastSlash) {
         return nullptr;
     }
 
diff --git a/libs/androidfw/tests/ApkParsing_test.cpp b/libs/androidfw/tests/ApkParsing_test.cpp
index 4aab0a146ecf..62e88c619e5c 100644
--- a/libs/androidfw/tests/ApkParsing_test.cpp
+++ b/libs/androidfw/tests/ApkParsing_test.cpp
@@ -68,4 +68,10 @@ TEST(ApkParsingTest, InvalidSubdirectories) {
   auto lastSlash = util::ValidLibraryPathLastSlash(path, false, false);
   ASSERT_THAT(lastSlash, IsNull());
 }
+
+TEST(ApkParsingTest, InvalidFileAtRoot) {
+  const char* path = "lib/library.so";
+  auto lastSlash = util::ValidLibraryPathLastSlash(path, false, false);
+  ASSERT_THAT(lastSlash, IsNull());
+}
 }
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