@@ -80,6 +80,11 @@ Deprecated and removed features, and other changes affecting compatibility:
of GNU libc are advised to check whether their build processes can be
simplified.
+* The dynamic linker calls the malloc and free functions in more cases
+ if a shared object with dynamic TLS is loaded and unloaded. This can
+ result in an infinite recursion if a malloc replacement libraries or
+ its dependencies uses dynamic TLS instead of initial-exec TLS.
+
* The ia64*-*-linux-gnu configurations are no longer supported.
Changes to build and runtime requirements:
@@ -1815,6 +1815,14 @@ using shared object dependencies or @code{LD_PRELOAD}. For static
linking, the @code{malloc} replacement library must be linked in before
linking against @code{libc.a} (explicitly or implicitly).
+Care must be taken not to use functionality from @theglibc{} that uses
+@code{malloc} internally. For example, the @code{fopen},
+@code{opendir}, @code{dlopen}, and @code{pthread_setspecific} functions
+currently use the @code{malloc} subsystem internally. If the
+replacement @code{malloc} or its dependencies use thread-local storage
+(TLS), it must use the initial-exec TLS model, and not one of the
+dynamic TLS variants.
+
@strong{Note:} Failure to provide a complete set of replacement
functions (that is, all the functions used by the application,
@theglibc{}, and other linked-in libraries) can lead to static linking
The increased malloc subsystem usage is a side effect of commit d2123d68275acc0f061e73d5f86ca504e0d5a344 ("elf: Fix slow tls access after dlopen [BZ #19924]"). --- NEWS | 5 +++++ manual/memory.texi | 8 ++++++++ 2 files changed, 13 insertions(+)