[Openmp-commits] [openmp] 402981e - [OpenMP][libomp] Remove false positive for memory sanitizer

[Jonathan Peyton via Openmp-commits]

Author: Jonathan Peyton
Date: 2023-02-06T09:30:21-06:00
New Revision: 402981ee25fe135d63226a7de17dbb14c437c71b

URL: https://github.com/llvm/llvm-project/commit/402981ee25fe135d63226a7de17dbb14c437c71b
DIFF: https://github.com/llvm/llvm-project/commit/402981ee25fe135d63226a7de17dbb14c437c71b.diff

LOG: [OpenMP][libomp] Remove false positive for memory sanitizer

The memory sanitizer intercepts the memcpy() call but not the direct
assignment of last byte to 0. This leads the sanitizer to believe the
last byte of a string based on the kmp_str_buf_t type is uninitialized.
Hence, the eventual strlen() inside __kmp_env_dump() leads to an
use-of-uninitialized-value warning.

Using strncat() instead gives the sanitizer the information it needs.

Differential Revision: https://reviews.llvm.org/D143401

Fixes #60501

Added: 
    

Modified: 
    openmp/runtime/src/kmp_safe_c_api.h
    openmp/runtime/src/kmp_str.cpp

Removed: 
    


################################################################################
diff  --git a/openmp/runtime/src/kmp_safe_c_api.h b/openmp/runtime/src/kmp_safe_c_api.h
index 3db1ada37b07b..72f26fd9897d0 100644
--- a/openmp/runtime/src/kmp_safe_c_api.h
+++ b/openmp/runtime/src/kmp_safe_c_api.h
@@ -30,6 +30,7 @@
 #define KMP_SSCANF sscanf_s
 #define KMP_STRCPY_S strcpy_s
 #define KMP_STRNCPY_S strncpy_s
+#define KMP_STRNCAT_S strncat_s
 
 // Use this only when buffer size is unknown
 #define KMP_MEMCPY(dst, src, cnt) memcpy_s(dst, cnt, src, cnt)
@@ -61,6 +62,7 @@ template <typename T> struct kmp_get_rmax_t<T, true> {
 #define KMP_SSCANF sscanf
 #define KMP_STRCPY_S(dst, bsz, src) strcpy(dst, src)
 #define KMP_STRNCPY_S(dst, bsz, src, cnt) strncpy(dst, src, cnt)
+#define KMP_STRNCAT_S(dst, bsz, src, cnt) strncat(dst, src, cnt)
 #define KMP_VSNPRINTF vsnprintf
 #define KMP_STRNCPY strncpy
 #define KMP_STRLEN strlen

diff  --git a/openmp/runtime/src/kmp_str.cpp b/openmp/runtime/src/kmp_str.cpp
index e64f989fbc698..41e4148cfe3c5 100644
--- a/openmp/runtime/src/kmp_str.cpp
+++ b/openmp/runtime/src/kmp_str.cpp
@@ -137,8 +137,7 @@ void __kmp_str_buf_cat(kmp_str_buf_t *buffer, char const *str, size_t len) {
   KMP_DEBUG_ASSERT(len >= 0);
 
   __kmp_str_buf_reserve(buffer, buffer->used + len + 1);
-  KMP_MEMCPY(buffer->str + buffer->used, str, len);
-  buffer->str[buffer->used + len] = 0;
+  KMP_STRNCAT_S(buffer->str + buffer->used, len + 1, str, len);
   __kmp_type_convert(buffer->used + len, &(buffer->used));
   KMP_STR_BUF_INVARIANT(buffer);
 } // __kmp_str_buf_cat
@@ -151,8 +150,7 @@ void __kmp_str_buf_catbuf(kmp_str_buf_t *dest, const kmp_str_buf_t *src) {
   if (!src->str || !src->used)
     return;
   __kmp_str_buf_reserve(dest, dest->used + src->used + 1);
-  KMP_MEMCPY(dest->str + dest->used, src->str, src->used);
-  dest->str[dest->used + src->used] = 0;
+  KMP_STRNCAT_S(dest->str + dest->used, src->used + 1, src->str, src->used);
   dest->used += src->used;
   KMP_STR_BUF_INVARIANT(dest);
 } // __kmp_str_buf_catbuf