[compiler-rt] [compiler-rt] [sanitizer_common] Add a testcase reproducing SIGSEGV in ForEachMappedRegion (PR #208358)

[Mike Kruskal via llvm-commits]

https://github.com/mkruskal-google updated https://github.com/llvm/llvm-project/pull/208358

>From f05f412150992bfe8824afb6f30f2b53ff99c244 Mon Sep 17 00:00:00 2001
From: Mike Kruskal <mkruskal at google.com>
Date: Sat, 27 Jun 2026 19:45:01 -0700
Subject: [PATCH 1/2] Add a testcase reproducing #84482 and #21068

---
 .../TestCases/Linux/dlopen_image_base.c       | 55 +++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c

diff --git a/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c b/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c
new file mode 100644
index 0000000000000..c7f7639f4c446
--- /dev/null
+++ b/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c
@@ -0,0 +1,55 @@
+/* RUN: %clang_msan -g %s -o %t
+   RUN: %clang_msan -g %s -DBUILD_SO -fPIC -o %t-so.so -shared -Wl,--image-base=0x4000000
+   RUN: %run %t 2>&1
+   REQUIRES: lld-available
+   REQUIRES: glibc
+   XFAIL: msan, dfsan
+*/
+
+#ifndef BUILD_SO
+#define _GNU_SOURCE
+#include <assert.h>
+#include <dlfcn.h>
+#include <link.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+  char path[4096];
+  snprintf(path, sizeof(path), "%s-so.so", argv[0]);
+
+  void *handle = dlopen(path, RTLD_LAZY);
+  if (!handle) {
+    fprintf(stderr, "dlopen failed: %s\n", dlerror());
+    return 1;
+  }
+
+  struct link_map *map = NULL;
+  dlinfo(handle, RTLD_DI_LINKMAP, &map);
+  if (map) {
+    printf("DSO link_map name: %s\n", map->l_name);
+    printf("DSO link_map l_addr: %p\n", (void*)map->l_addr);
+    int pipefd[2];
+    bool readable = false;
+    if (pipe(pipefd) == 0) {
+      if (write(pipefd[1], (void*)map->l_addr, 1) == 1) {
+        readable = true;
+      }
+      close(pipefd[0]);
+      close(pipefd[1]);
+    }
+    printf("DSO l_addr readable: %d\n", readable);
+  }
+
+  void (*fn)() = (void (*)())dlsym(handle, "fn");
+  assert(fn != NULL);
+  fn();
+
+  dlclose(handle);
+  return 0;
+}
+#else // BUILD_SO
+#include <stdio.h>
+void fn() { printf("DSO function called successfully\n"); }
+#endif

>From 95638bf8628134b115a99b2f4820ef8e026be25b Mon Sep 17 00:00:00 2001
From: Mike Kruskal <mkruskal at google.com>
Date: Wed, 8 Jul 2026 18:05:52 -0700
Subject: [PATCH 2/2] Fix formatting

---
 .../TestCases/Linux/dlopen_image_base.c       | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c b/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c
index c7f7639f4c446..e340d0bd2bfe2 100644
--- a/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c
+++ b/compiler-rt/test/sanitizer_common/TestCases/Linux/dlopen_image_base.c
@@ -7,13 +7,13 @@
 */
 
 #ifndef BUILD_SO
-#define _GNU_SOURCE
-#include <assert.h>
-#include <dlfcn.h>
-#include <link.h>
-#include <stdbool.h>
-#include <stdio.h>
-#include <unistd.h>
+#  define _GNU_SOURCE
+#  include <assert.h>
+#  include <dlfcn.h>
+#  include <link.h>
+#  include <stdbool.h>
+#  include <stdio.h>
+#  include <unistd.h>
 
 int main(int argc, char *argv[]) {
   char path[4096];
@@ -29,11 +29,11 @@ int main(int argc, char *argv[]) {
   dlinfo(handle, RTLD_DI_LINKMAP, &map);
   if (map) {
     printf("DSO link_map name: %s\n", map->l_name);
-    printf("DSO link_map l_addr: %p\n", (void*)map->l_addr);
+    printf("DSO link_map l_addr: %p\n", (void *)map->l_addr);
     int pipefd[2];
     bool readable = false;
     if (pipe(pipefd) == 0) {
-      if (write(pipefd[1], (void*)map->l_addr, 1) == 1) {
+      if (write(pipefd[1], (void *)map->l_addr, 1) == 1) {
         readable = true;
       }
       close(pipefd[0]);
@@ -50,6 +50,6 @@ int main(int argc, char *argv[]) {
   return 0;
 }
 #else // BUILD_SO
-#include <stdio.h>
+#  include <stdio.h>
 void fn() { printf("DSO function called successfully\n"); }
 #endif