Merge pull request systemd#19662 from yuwata/memdup

poettering · web-flow · commit 2adcf6f4f7d1 · 2021-05-19T23:24:55.000+02:00
util: make memdup() or friends safer
diff --git a/src/basic/alloc-util.c b/src/basic/alloc-util.c
@@ -17,8 +17,7 @@ void* memdup(const void *p, size_t l) {
         if (!ret)
                 return NULL;
 
-        memcpy(ret, p, l);
-        return ret;
+        return memcpy_safe(ret, p, l);
 }
 
 void* memdup_suffix0(const void *p, size_t l) {
@@ -35,8 +34,8 @@ void* memdup_suffix0(const void *p, size_t l) {
         if (!ret)
                 return NULL;
 
-        *((uint8_t*) mempcpy(ret, p, l)) = 0;
-        return ret;
+        ((uint8_t*) ret)[l] = 0;
+        return memcpy_safe(ret, p, l);
 }
 
 void* greedy_realloc(
diff --git a/src/basic/alloc-util.h b/src/basic/alloc-util.h
@@ -66,7 +66,7 @@ void* memdup_suffix0(const void *p, size_t l); /* We can't use _alloc_() here, s
                 size_t _l_ = l;                 \
                 assert(_l_ <= ALLOCA_MAX);      \
                 _q_ = alloca(_l_ ?: 1);         \
-                memcpy(_q_, p, _l_);            \
+                memcpy_safe(_q_, p, _l_);       \
         })
 
 #define memdupa_suffix0(p, l)                   \
@@ -76,7 +76,7 @@ void* memdup_suffix0(const void *p, size_t l); /* We can't use _alloc_() here, s
                 assert(_l_ <= ALLOCA_MAX);      \
                 _q_ = alloca(_l_ + 1);          \
                 ((uint8_t*) _q_)[_l_] = 0;      \
-                memcpy(_q_, p, _l_);            \
+                memcpy_safe(_q_, p, _l_);       \
         })
 
 static inline void freep(void *p) {
diff --git a/src/basic/memory-util.h b/src/basic/memory-util.h
@@ -16,11 +16,11 @@ size_t page_size(void) _pure_;
 #define PAGE_OFFSET(l) ((l) & (page_size() - 1))
 
 /* Normal memcpy requires src to be nonnull. We do nothing if n is 0. */
-static inline void memcpy_safe(void *dst, const void *src, size_t n) {
+static inline void *memcpy_safe(void *dst, const void *src, size_t n) {
         if (n == 0)
-                return;
+                return dst;
         assert(src);
-        memcpy(dst, src, n);
+        return memcpy(dst, src, n);
 }
 
 /* Normal memcmp requires s1 and s2 to be nonnull. We do nothing if n is 0. */
