Merge pull request #12047 from poettering/cryptsetup-fixlets

some small cryptsetup, ask-password and allocation fixlets

src/basic/alloc-util.c

@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
+#include <malloc.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -27,6 +28,9 @@ void* memdup_suffix0(const void *p, size_t l) {
 
         /* The same as memdup() but place a safety NUL byte after the allocated memory */
 
+        if (_unlikely_(l == SIZE_MAX)) /* prevent overflow */
+                return NULL;
+
         ret = malloc(l + 1);
         if (!ret)
                 return NULL;
@@ -45,19 +49,23 @@ void* greedy_realloc(void **p, size_t *allocated, size_t need, size_t size) {
         if (*allocated >= need)
                 return *p;
 
-        newalloc = MAX(need * 2, 64u / size);
-        a = newalloc * size;
-
-        /* check for overflows */
-        if (a < size * need)
+        if (_unlikely_(need > SIZE_MAX/2)) /* Overflow check */
                 return NULL;
 
+        newalloc = need * 2;
+        if (size_multiply_overflow(newalloc, size))
+                return NULL;
+
+        a = newalloc * size;
+        if (a < 64) /* Allocate at least 64 bytes */
+                a = 64;
+
         q = realloc(*p, a);
         if (!q)
                 return NULL;
 
         *p = q;
-        *allocated = newalloc;
+        *allocated = _unlikely_(size == 0) ? newalloc : malloc_usable_size(q) / size;
         return q;
 }
 

src/basic/alloc-util.h

@@ -156,8 +156,8 @@ void* greedy_realloc0(void **p, size_t *allocated, size_t need, size_t size);
                 (void*)memset(_new_, 0, _xsize_);                       \
         })
 
-/* Takes inspiration from Rusts's Option::take() method: reads and returns a pointer, but at the same time resets it to
- * NULL. See: https://doc.rust-lang.org/std/option/enum.Option.html#method.take */
+/* Takes inspiration from Rust's Option::take() method: reads and returns a pointer, but at the same time
+ * resets it to NULL. See: https://doc.rust-lang.org/std/option/enum.Option.html#method.take */
 #define TAKE_PTR(ptr)                           \
         ({                                      \
                 typeof(ptr) _ptr_ = (ptr);      \

src/basic/memory-util.h

@@ -77,3 +77,8 @@ static inline void* explicit_bzero_safe(void *p, size_t l) {
 #else
 void *explicit_bzero_safe(void *p, size_t l);
 #endif
+
+/* Use with _cleanup_ to erase a single 'char' when leaving scope */
+static inline void erase_char(char *p) {
+        explicit_bzero_safe(p, sizeof(char));
+}