* [Bug malloc/23328] Remove malloc hooks and ensure related APIs return no data.
[not found] <bug-23328-131@http.sourceware.org/bugzilla/>
2021-07-14 2:42 ` [Bug malloc/23328] Remove malloc hooks and ensure related APIs return no data siddhesh at sourceware dot org
@ 2021-07-22 13:19 ` siddhesh at sourceware dot org
2021-07-30 7:15 ` i at maskray dot me
2021-08-05 18:19 ` i at maskray dot me
3 siblings, 0 replies; 4+ messages in thread
From: siddhesh at sourceware dot org @ 2021-07-22 13:19 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=23328
Siddhesh Poyarekar <siddhesh at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |2.34
--- Comment #5 from Siddhesh Poyarekar <siddhesh at sourceware dot org> ---
commit 1e5a5866cb9541b5231dba3d86c8a1a35d516de9
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:12 2021 +0530
Remove malloc hooks [BZ #23328]
Make malloc hooks symbols compat-only so that new applications cannot
link against them and remove the declarations from the API. Also
remove the unused malloc-hooks.h.
Finally, mark all symbols in libc_malloc_debug.so as compat so that
the library cannot be linked against.
Add a note about the deprecation in NEWS.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit 0552fd2c7d4e8a570cb4fe4dfe65e96f6d24b0cd
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:10 2021 +0530
Move malloc_{g,s}et_state to libc_malloc_debug
These deprecated functions are only safe to call from
__malloc_initialize_hook and as a result, are not useful in the
general case. Move the implementations to libc_malloc_debug so that
existing binaries that need it will now have to preload the debug DSO
to work correctly.
This also allows simplification of the core malloc implementation by
dropping all the undumping support code that was added to make
malloc_set_state work.
One known breakage is that of ancient emacs binaries that depend on
this. They will now crash when running with this libc. With
LD_BIND_NOW=1, it will terminate immediately because of not being able
to find malloc_set_state but with lazy binding it will crash in
unpredictable ways. It will need a preloaded libc_malloc_debug.so so
that its initialization hook is executed to allow its malloc
implementation to work properly.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit b5bd5bfe88f496463ec9fab680a8edf64d7c2a42
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:08 2021 +0530
glibc.malloc.check: Wean away from malloc hooks
The malloc-check debugging feature is tightly integrated into glibc
malloc, so thanks to an idea from Florian Weimer, much of the malloc
implementation has been moved into libc_malloc_debug.so to support
malloc-check. Due to this, glibc malloc and malloc-check can no
longer work together; they use altogether different (but identical)
structures for heap management. This should not make a difference
though since the malloc check hook is not disabled anywhere.
malloc_set_state does, but it does so early enough that it shouldn't
cause any problems.
The malloc check tunable is now in the debug DSO and has no effect
when the DSO is not preloaded.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit 9dad716d4d2993f50b165747781244bd7c43bc95
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:06 2021 +0530
mtrace: Wean away from malloc hooks
Wean mtrace away from the malloc hooks and move them into the debug
DSO. Split the API away from the implementation so that we can add
the API to libc.so as well as libc_malloc_debug.so, with the libc
implementations being empty.
Update localplt data since memalign no longer has any callers after
this change.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit cc35896ea3e4532919ec81b17f36299117debe79
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:04 2021 +0530
Simplify __malloc_initialized
Now that mcheck no longer needs to check __malloc_initialized (and no
other third party hook can since the symbol is not exported), make the
variable boolean and static so that it is used strictly within malloc.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit c142eb253f3814f46527e9b37484041dd85702cf
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:38:02 2021 +0530
mcheck: Wean away from malloc hooks [BZ #23489]
Split the mcheck implementation into the debugging hooks and API so
that the API can be replicated in libc and libc_malloc_debug.so. The
libc APIs always result in failure.
The mcheck implementation has also been moved entirely into
libc_malloc_debug.so and with it, all of the hook initialization code
can now be moved into the debug library. Now the initialization can
be done independently of libc internals.
With this patch, libc_malloc_debug.so can no longer be used with older
libcs, which is not its goal anyway. tst-vfork3 breaks due to this
since it spawns shell scripts, which in turn execute using the system
glibc. Move the test to tests-container so that only the built glibc
is used.
This move also fixes bugs in the mcheck version of memalign and
realloc, thus allowing removal of the tests from tests-mcheck
exclusion list.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit 2d2d9f2b48a943fa556301db532103d09800da4d
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:37:59 2021 +0530
Move malloc hooks into a compat DSO
Remove all malloc hook uses from core malloc functions and move it
into a new library libc_malloc_debug.so. With this, the hooks now no
longer have any effect on the core library.
libc_malloc_debug.so is a malloc interposer that needs to be preloaded
to get hooks functionality back so that the debugging features that
depend on the hooks, i.e. malloc-check, mcheck and mtrace work again.
Without the preloaded DSO these debugging features will be nops.
These features will be ported away from hooks in subsequent patches.
Similarly, legacy applications that need hooks functionality need to
preload libc_malloc_debug.so.
The symbols exported by libc_malloc_debug.so are maintained at exactly
the same version as libc.so.
Finally, static binaries will no longer be able to use malloc
debugging features since they cannot preload the debugging DSO.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit 55a4dd39308951da4b0da84b19e415c2bb451b60
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:37:57 2021 +0530
Remove __morecore and __default_morecore
Make the __morecore and __default_morecore symbols compat-only and
remove their declarations from the API. Also, include morecore.c
directly into malloc.c; this should ideally get merged into malloc in
a future cleanup.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
commit 57b07bede12635bd6d6aa0e488824bb510bbeca4
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Thu Jul 22 18:37:54 2021 +0530
Remove __after_morecore_hook
Remove __after_morecore_hook from the API and finalize the symbol so
that it can no longer be used in new applications. Old applications
using __after_morecore_hook will find that their hook is no longer
called.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
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