Author: Carlos O'Donell <email@example.com>
Date: Mon Apr 8 17:35:05 2019 -0400
malloc: Set and reset all hooks for tracing (Bug 16573)
If an error occurs during the tracing operation, particularly during a
call to lock_and_info() which calls _dl_addr, we may end up calling back
into the malloc-subsystem and relock the loader lock and deadlock. For
all intents and purposes the call to _dl_addr can call any of the malloc
family API functions and so we should disable all tracing before calling
such loader functions. This is similar to the strategy that the new
malloc tracer takes when calling the real malloc, namely that all
tracing ceases at the boundary to the real function and any faults at
that point are the purvue of the library (though the new tracer does
this on a per-thread basis in an MT-safe fashion). Since the new tracer
and the hook deprecation are not yet complete we must fix these issues
where we can.
Tested on x86_64 with no regressions.
Co-authored-by: Kwok Cheung Yeung <firstname.lastname@example.org>
Reviewed-by: DJ Delorie <email@example.com>
Please also verify upstream branch backports:
release/2.30/master - May be required. Please check.
release/2.29/master - May be required. Please check.
release/2.28/master - May be required. Please check.
Verified with a test case from https://sourceware.org/bugzilla/show_bug.cgi?id=16573, it doesn't hang:
[root@host bz1764235-glibc-malloc-Set-and-reset-all-hooks-for-tracing]# cat mtrace_test.c
a = (char*) malloc(8);
[root@host bz1764235-glibc-malloc-Set-and-reset-all-hooks-for-tracing]# gcc mtrace_test.c -o mtrace_test
[root@host bz1764235-glibc-malloc-Set-and-reset-all-hooks-for-tracing]# MALLOC_TRACE='mtrace.log' ./mtrace_test
free(): double free detected in tcache 2
Aborted (core dumped)
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.