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muntrace: reset file and hooks before finalizing the stream

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fclose will call free, invoking its hook, then fprintf which would indirectly
try to allocate a buffer, and this can cause malloc to be used (thus its hook
to be invoked) if libio uses malloc instead of mmap; given any malloc/free hook
locks the internal lock, this leads to a deadlock.

To prevent this hook roundtrip at muntrace, first unset MALLSTREAM and the
hooks, and only after that close the trace file.
This commit is contained in:
Pino Toscano 2012-11-19 20:01:00 +01:00
parent 942caa1656
commit e19af3803b
2 changed files with 10 additions and 2 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2012-11-19 Pino Toscano <toscano.pino@tiscali.it>
* malloc/mtrace.c (muntrace): Reset MALLSTREAM and the hooks before
finalizing MALLSTREAM.
* sysdeps/mach/hurd/syncfs.c: New file.
2012-11-19 Siddhesh Poyarekar <siddhesh@redhat.com>

9
malloc/mtrace.c
View File

@ -364,11 +364,16 @@ muntrace ()
if (mallstream == NULL)
return;
fprintf (mallstream, "= End\n");
fclose (mallstream);
/* Do the reverse of what done in mtrace: first reset the hooks and
MALLSTREAM, and only after that write the trailer and close the
file. */
FILE *f = mallstream;
mallstream = NULL;
__free_hook = tr_old_free_hook;
__malloc_hook = tr_old_malloc_hook;
__realloc_hook = tr_old_realloc_hook;
__memalign_hook = tr_old_memalign_hook;
fprintf (f, "= End\n");
fclose (f);
}