Stop using malloc_usable_size and malloc_size

Although the nanual page of malloc_usable_size says:

    Although the excess bytes can be over‐written by the application
    without ill effects, this is not good programming practice: the
    number of excess bytes in an allocation depends on the underlying
    implementation.

it looks like the premise is broken with _FORTIFY_SOURCE=3 on newer
systems and it might return a value that causes program to stop with
"buffer overflow" detected from the _FORTIFY_SOURCE.  As we do have own
implementation that tracks the allocation size that we can use to track
the allocation size, we can stop relying on this introspection function.

Also the newer manual page for malloc_usable_size changed the NOTES to:

    The value returned by malloc_usable_size() may be greater than the
    requested size of the allocation because of various internal
    implementation details, none of which the programmer should rely on.
    This function is intended to only be used for diagnostics and
    statistics; writing to the excess memory without first calling
    realloc(3) to resize the allocation is not supported.  The returned
    value is only valid at the time of the call.

Remove usage of both malloc_usable_size() and malloc_size() to be on the
safe size and only use the internal size tracking mechanism when
jemalloc is not available.

(cherry picked from commit d61712d14e5aeb179b3ea54a71a599927425732a)

diff --git a/configure.ac b/configure.ac
index 87640ae43b429886e8bb6ed3cc6d6aefc691ba97..1e80fba356144c8c985cf86ef4a2cefbf93d0fc7 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1301,8 +1301,7 @@ AS_CASE([$with_jemalloc],
 
 AS_IF([test "$with_jemalloc" = "no"],
       [AS_CASE([$host],
-              [*-freebsd*],[AC_MSG_ERROR([You cannot compile without jemalloc; jemalloc is the system allocator on FreeBSD])])
-       AC_CHECK_FUNCS([malloc_size malloc_usable_size])])
+              [*-freebsd*],[AC_MSG_ERROR([You cannot compile without jemalloc; jemalloc is the system allocator on FreeBSD])])])
 
 AM_CONDITIONAL([HAVE_JEMALLOC], [test "$with_jemalloc" = "yes"])
 

diff --git a/lib/isc/jemalloc_shim.h b/lib/isc/jemalloc_shim.h
index 493bf5ffc0dab5ba584e5dc17598feae35d12862..9f7bc9db31e968c208df002175c5c97e7a98ae6d 100644 (file)
--- a/lib/isc/jemalloc_shim.h
+++ b/lib/isc/jemalloc_shim.h
@@ -27,67 +27,6 @@ const char *malloc_conf = NULL;
 #define MALLOCX_TCACHE_NONE (0)
 #define MALLOCX_ARENA(a)    (0)
 
-#if defined(HAVE_MALLOC_SIZE) || defined(HAVE_MALLOC_USABLE_SIZE)
-
-#include <stdlib.h>
-
-static inline void *
-mallocx(size_t size, int flags) {
-       UNUSED(flags);
-
-       return (malloc(size));
-}
-
-static inline void
-sdallocx(void *ptr, size_t size, int flags) {
-       UNUSED(size);
-       UNUSED(flags);
-
-       free(ptr);
-}
-
-static inline void *
-rallocx(void *ptr, size_t size, int flags) {
-       UNUSED(flags);
-       REQUIRE(size != 0);
-
-       return (realloc(ptr, size));
-}
-
-#ifdef HAVE_MALLOC_SIZE
-
-#include <malloc/malloc.h>
-
-static inline size_t
-sallocx(void *ptr, int flags) {
-       UNUSED(flags);
-
-       return (malloc_size(ptr));
-}
-
-#elif HAVE_MALLOC_USABLE_SIZE
-
-#ifdef __DragonFly__
-/*
- * On DragonFly BSD 'man 3 malloc' advises us to include the following
- * header to have access to malloc_usable_size().
- */
-#include <malloc_np.h>
-#else
-#include <malloc.h>
-#endif
-
-static inline size_t
-sallocx(void *ptr, int flags) {
-       UNUSED(flags);
-
-       return (malloc_usable_size(ptr));
-}
-
-#endif /* HAVE_MALLOC_SIZE */
-
-#else /* defined(HAVE_MALLOC_SIZE) || defined (HAVE_MALLOC_USABLE_SIZE) */
-
 #include <stdlib.h>
 
 typedef union {
@@ -111,21 +50,16 @@ mallocx(size_t size, int flags) {
 }
 
 static inline void
-sdallocx(void *ptr, size_t size, int flags) {
+sdallocx(void *ptr, size_t size ISC_ATTR_UNUSED, int flags ISC_ATTR_UNUSED) {
        size_info *si = &(((size_info *)ptr)[-1]);
 
-       UNUSED(size);
-       UNUSED(flags);
-
        free(si);
 }
 
 static inline size_t
-sallocx(void *ptr, int flags) {
+sallocx(void *ptr, int flags ISC_ATTR_UNUSED) {
        size_info *si = &(((size_info *)ptr)[-1]);
 
-       UNUSED(flags);
-
        return (si[0].size);
 }
 
@@ -144,6 +78,4 @@ rallocx(void *ptr, size_t size, int flags) {
        return (ptr);
 }
 
-#endif /* defined(HAVE_MALLOC_SIZE) || defined (HAVE_MALLOC_USABLE_SIZE) */
-
 #endif /* !defined(HAVE_JEMALLOC) */