Make mremap work after PR_SET_VMA_ANON_NAME.

rr-debugger · Jun 2, 2024 · 7c5846e · 7c5846e
1 parent 3f251e0
commit 7c5846e
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Showing 3 changed files with 13 additions and 1 deletion.
diff --git a/src/AddressSpace.h b/src/AddressSpace.h
@@ -152,6 +152,9 @@ class KernelMapping : public MemoryRange {
   bool is_stack() const { return fsname().find("[stack") == 0; }
   bool is_vvar() const { return fsname() == "[vvar]"; }
   bool is_vsyscall() const { return fsname() == "[vsyscall]"; }
+  bool is_named_anonymous() const {
+    return fsname().find("[anon:") == 0 || fsname().find("[anon_shmem:") == 0;
+  }
 
   struct stat fake_stat() const {
     struct stat fake_stat;

diff --git a/src/replay_syscall.cc b/src/replay_syscall.cc
@@ -820,7 +820,8 @@ static void process_mremap(ReplayTask* t, const TraceFrame& trace_frame,
   auto f = mapping.emu_file;
   if (f) {
     f->ensure_size(mapping.map.file_offset_bytes() + new_size);
-  } else if (new_size > old_size && mapping.map.fsname().size() > 0) {
+  } else if (new_size > old_size && mapping.map.fsname().size() > 0 &&
+             !mapping.map.is_named_anonymous()) {
     struct stat st;
     int ret = stat(mapping.map.fsname().c_str(), &st);
     if (ret != 0) {

diff --git a/src/test/prctl_anon_vma_name.c b/src/test/prctl_anon_vma_name.c
@@ -37,6 +37,14 @@ int main(void) {
     test_assert(p2 != MAP_FAILED);
     ret = prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p, page_size*4, "ghi");
     test_assert(ret == -1 && errno == EBADF);
+
+    char* p3 = (char*)mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+        MAP_ANONYMOUS | (i ? MAP_SHARED : MAP_PRIVATE), -1, 0);
+    test_assert(p != MAP_FAILED);
+
+    ret = prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p3, page_size, "don't blow up");
+    test_assert(ret == 0);
+    p3 = mremap(p3, page_size, 2*page_size, MREMAP_MAYMOVE);
   }
 
   atomic_puts("EXIT-SUCCESS");