[DragonFlyBSD - Bug #2305] (In Progress) dmalloc calls malloc before malloc_init constructor called.

Venkatesh Srinivas via Redmine bugtracker-admin at leaf.dragonflybsd.org
Wed May 23 10:29:52 PDT 2012


Issue #2305 has been updated by Venkatesh Srinivas.

Status changed from Resolved to In Progress

Spoke too soon. The commit broke libc's interactions with libpthread programs on x86-64 and was quickly reverted. (pthreaded programs which used preinit functions which allocated memory were okay.)

The problem with the earlier commit was -- if libpthread's init code (_libpthread_init) was called via an attribute constructor before malloc was initialized, it would try to set up a redzone for thread 0 and then call thr_alloc, which would try _nmalloc_thr_init. _nmalloc_thr_init itself would then try to initialize libpthread, which would fail on the second attempt to set up the redzone.


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Bug #2305: dmalloc calls malloc before malloc_init constructor called.
http://bugs.dragonflybsd.org/issues/2305

Author: John Marino
Status: In Progress
Priority: Normal
Assignee: Venkatesh Srinivas
Category: 
Target version: 


During the development of the .preinit_array ELF section support, it was discovered that a test passed on i386 but failed on x86_64 regardless if the binary was statically or dynamically linked.  The program segfaulted on the first preinit function in the dmalloc function.

i386 uses nmalloc rather than dmalloc and the preinit test case passes just fine on that architecture.

The test case is here: http://leaf.dragonflybsd.org/~marino/preinit.c
The backtrace:
Program received signal SIGSEGV, Segmentation fault.
0x0000000800891269 in slaballoc (chunk_size=<optimized out>, chunking=<optimized out>, zi=<optimized out>)
    at /usr/src/lib/libc/../libc/stdlib/dmalloc.c:1069
1069		while ((slab = zinfo->avail_base) != NULL) {
#0  0x0000000800891269 in slaballoc (chunk_size=<optimized out>, chunking=<optimized out>, zi=<optimized out>)
    at /usr/src/lib/libc/../libc/stdlib/dmalloc.c:1069
#1  memalloc (size=4096, flags=0) at /usr/src/lib/libc/../libc/stdlib/dmalloc.c:744
#2  0x0000000800891cf1 in malloc (size=1344) at /usr/src/lib/libc/../libc/stdlib/dmalloc.c:593
#3  0x00000008008fe89b in __smakebuf (fp=0x800b2e850) at /usr/src/lib/libc/../libc/stdio/makebuf.c:70
#4  0x00000008008fe74f in __swsetup (fp=0x800b2e850) at /usr/src/lib/libc/../libc/stdio/wsetup.c:79
#5  0x00000008008fde15 in __sfvwrite (fp=0x800b2e850, uio=0x0) at /usr/src/lib/libc/../libc/stdio/fvwrite.c:62
#6  0x00000008008e6473 in puts (s=0x540 <Address 0x540 out of bounds>) at /usr/src/lib/libc/../libc/stdio/puts.c:65
#7  0x0000000000400742 in preinit_0 () at preinit.c:6
#8  0x000000080060ba71 in preinitialize_main_object () at /usr/src/libexec/rtld-elf/rtld.c:2051
#9  _rtld_call_init () at /usr/src/libexec/rtld-elf/rtld.c:703
#10 0x00000000004005ba in _start (ap=<optimized out>, cleanup=0x80060d65b <rtld_exit>)
    at /usr/src/lib/csu/x86_64/crt1.c:96



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