Add $ORIGIN to fuzzer-coverage sanitized .so's.
Build fuzzer-sanitized libraries with an $ORIGIN DT_RUNPATH. Android's linker
uses DT_RUNPATH, not DT_RPATH. When we deploy cc_fuzz targets and their
libraries to /data/fuzz/<arch>/lib, any transient shared library gets the
DT_RUNPATH from the shared library above it, and not the executable, meaning
that the lookup falls back to the system. Adding the $ORIGIN to the DT_RUNPATH
here means that transient shared libraries can be found colocated with their
parents.
This may have some interesting consequences if:
1. Your fuzz target depends on a shared library which has `sanitize.fuzzer:
false` (as the DT_RUNPATH won't have `$ORIGIN`, and so you may get missing
libraries).
2. A `SANITIZE_TARGET=fuzzer` platform has a shared object in two
different directories (like system vs. ndk) and is depending on the linker
implementation details to resolve this in some manner.
I don't believe either of these instances should reasonably happen in
practise.
Fixes: 145973404
Fixes: 145988908
Test: m example_fuzzer
Change-Id: I94cbf628fc1ce15c43283d72bdabd9817de1fef8
diff --git a/cc/sanitize.go b/cc/sanitize.go
index b4082d3..c4aeb96 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -494,6 +494,15 @@
// Disable fortify for fuzzing builds. Generally, we'll be building with
// UBSan or ASan here and the fortify checks pollute the stack traces.
flags.Local.CFlags = append(flags.Local.CFlags, "-U_FORTIFY_SOURCE")
+
+ // Build fuzzer-sanitized libraries with an $ORIGIN DT_RUNPATH. Android's
+ // linker uses DT_RUNPATH, not DT_RPATH. When we deploy cc_fuzz targets and
+ // their libraries to /data/fuzz/<arch>/lib, any transient shared library gets
+ // the DT_RUNPATH from the shared library above it, and not the executable,
+ // meaning that the lookup falls back to the system. Adding the $ORIGIN to the
+ // DT_RUNPATH here means that transient shared libraries can be found
+ // colocated with their parents.
+ flags.Local.LdFlags = append(flags.Local.LdFlags, `-Wl,-rpath,\$$ORIGIN`)
}
if Bool(sanitize.Properties.Sanitize.Cfi) {