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[msan] Don't unpoison phdrs on dlopen(NULL, 0) 

Summary:
dlopen(NULL, ...) is intended to give you back a handle to the
executable for use with dlsym. Casting it to link_map and using it with
ForEachMappedRegion results in a crash.

We also shouldn't unpoison the globals of a DSO that is already in
memory. This ensures that we don't do it for the executable, but in
general, MSan may have false negatives if the DSO is already loaded.

Reviewers: eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14795

llvm-svn: 253530
This commit is contained in:
Reid Kleckner 2015-11-19 00:55:45 +00:00
parent 3afb80e375
commit 4029426b17
2 changed files with 22 additions and 4 deletions
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9
compiler-rt/lib/msan/msan_interceptors.cc
View File

@ -1434,10 +1434,11 @@ int OnExit() {
} while (false) // FIXME
#define COMMON_INTERCEPTOR_BLOCK_REAL(name) REAL(name)
#define COMMON_INTERCEPTOR_ON_EXIT(ctx) OnExit()
#define COMMON_INTERCEPTOR_LIBRARY_LOADED(filename, handle) \
do { \
link_map *map = GET_LINK_MAP_BY_DLOPEN_HANDLE((handle)); \
if (map) ForEachMappedRegion(map, __msan_unpoison); \
#define COMMON_INTERCEPTOR_LIBRARY_LOADED(filename, handle) \
do { \
link_map *map = GET_LINK_MAP_BY_DLOPEN_HANDLE((handle)); \
if (filename && map) \
ForEachMappedRegion(map, __msan_unpoison); \
} while (false)
#define COMMON_INTERCEPTOR_GET_TLS_RANGE(begin, end) \

17
compiler-rt/test/msan/dlopen_executable.cc Normal file
View File

@ -0,0 +1,17 @@
// RUN: %clangxx_msan -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
#include <assert.h>
#include <dlfcn.h>
#include <stdlib.h>
static int my_global;
int main(void) {
int *uninit = (int*)malloc(sizeof(int));
my_global = *uninit;
void *p = dlopen(0, RTLD_NOW);
assert(p && "failed to get handle to executable");
return my_global;
// CHECK: MemorySanitizer: use-of-uninitialized-value
// CHECK: #0 {{.*}} in main{{.*}}dlopen_executable.cc:[[@LINE-2]]
}