[compiler-rt] Link shared sanitizer runtime with libresolv for dn_expand (PR #116415)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-pgo

Author: Aaron Puchert (aaronpuchert)

<details>
<summary>Changes</summary>

Since the interceptor was added in 1a729bce86173, a process using sanitizers might need libresolv for the real version of __dn_expand. The linker flag for the static runtime was added in 6dce56b2a3082. But the dynamic runtime didn't get the dependency. This can cause crashes even when libresolv is not used directly, because it is also used by DNS lookups via e.g. getaddrinfo when the DNS reply uses compression.

We observed the issue with the address sanitizer, but a quick look into the shared runtime libraries revealed that the memprof and tsan runtimes also export dn_expand and should thus be prone to the same issue.

It should be mentioned that glibc plans to move libresolv into libc, which was partially completed in version 2.34 with the move of dn_comp and dn_expand. However, that is not an issue here: once the move is complete, there will only be a static libresolv.a stub left and so building against a version after the move will no longer produce a runtime dependency to libresolv.so.

Fixes #<!-- -->59007.

---
Full diff: https://github.com/llvm/llvm-project/pull/116415.diff


4 Files Affected:

- (modified) compiler-rt/cmake/config-ix.cmake (+1) 
- (modified) compiler-rt/lib/asan/CMakeLists.txt (+1) 
- (modified) compiler-rt/lib/memprof/CMakeLists.txt (+1) 
- (modified) compiler-rt/lib/tsan/rtl/CMakeLists.txt (+1) 


``````````diff
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 6d52eecc9a91fe..74f7fb4ac4880f 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -189,6 +189,7 @@ check_include_files("sys/auxv.h"    COMPILER_RT_HAS_AUXV)
 # Libraries.
 check_library_exists(dl dlopen "" COMPILER_RT_HAS_LIBDL)
 check_library_exists(rt shm_open "" COMPILER_RT_HAS_LIBRT)
+check_library_exists(resolv dn_expand "" COMPILER_RT_HAS_LIBRESOLV)
 check_library_exists(m pow "" COMPILER_RT_HAS_LIBM)
 check_library_exists(pthread pthread_create "" COMPILER_RT_HAS_LIBPTHREAD)
 check_library_exists(execinfo backtrace "" COMPILER_RT_HAS_LIBEXECINFO)
diff --git a/compiler-rt/lib/asan/CMakeLists.txt b/compiler-rt/lib/asan/CMakeLists.txt
index fb3d74283a61e0..7a92a1a187a816 100644
--- a/compiler-rt/lib/asan/CMakeLists.txt
+++ b/compiler-rt/lib/asan/CMakeLists.txt
@@ -153,6 +153,7 @@ append_list_if(COMPILER_RT_HAS_LIBRT rt ASAN_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBM m ASAN_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBPTHREAD pthread ASAN_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBLOG log ASAN_DYNAMIC_LIBS)
+append_list_if(COMPILER_RT_HAS_LIBRESOLV resolv ASAN_DYNAMIC_LIBS)
 append_list_if(MINGW "${MINGW_LIBRARIES}" ASAN_DYNAMIC_LIBS)
 
 # Compile ASan sources into an object library.
diff --git a/compiler-rt/lib/memprof/CMakeLists.txt b/compiler-rt/lib/memprof/CMakeLists.txt
index e6d99daca6ee7d..2d0df65f43a260 100644
--- a/compiler-rt/lib/memprof/CMakeLists.txt
+++ b/compiler-rt/lib/memprof/CMakeLists.txt
@@ -74,6 +74,7 @@ append_list_if(COMPILER_RT_HAS_LIBRT rt MEMPROF_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBM m MEMPROF_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBPTHREAD pthread MEMPROF_DYNAMIC_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBLOG log MEMPROF_DYNAMIC_LIBS)
+append_list_if(COMPILER_RT_HAS_LIBRESOLV resolv MEMPROF_DYNAMIC_LIBS)
 
 # Compile MemProf sources into an object library.
 
diff --git a/compiler-rt/lib/tsan/rtl/CMakeLists.txt b/compiler-rt/lib/tsan/rtl/CMakeLists.txt
index f40e72dbde1f98..a6e9c7960fd594 100644
--- a/compiler-rt/lib/tsan/rtl/CMakeLists.txt
+++ b/compiler-rt/lib/tsan/rtl/CMakeLists.txt
@@ -20,6 +20,7 @@ set(TSAN_DYNAMIC_LINK_LIBS
 append_list_if(COMPILER_RT_HAS_LIBDL dl TSAN_DYNAMIC_LINK_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBM m TSAN_DYNAMIC_LINK_LIBS)
 append_list_if(COMPILER_RT_HAS_LIBPTHREAD pthread TSAN_DYNAMIC_LINK_LIBS)
+append_list_if(COMPILER_RT_HAS_LIBRESOLV resolv TSAN_DYNAMIC_LIBS)
 
 set(TSAN_SOURCES
   tsan_debugging.cpp

``````````

</details>


https://github.com/llvm/llvm-project/pull/116415