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authorCarlos O'Donell <carlos@redhat.com>2019-04-08 17:35:05 -0400
committerCarlos O'Donell <carlos@redhat.com>2019-04-09 10:56:51 -0400
commite621246ec6393ea08ae50310f9d5e72500f8c9bc (patch)
treee187de740537af6d7784784efc71a0936d5bfe7b /malloc
parent648279f4af423c4783ec1dfa63cb7b46a7640217 (diff)
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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 <kcy@codesourcery.com> Reviewed-by: DJ Delorie <dj@redhat.com>
Diffstat (limited to 'malloc')
-rw-r--r--malloc/mtrace.c72
1 files changed, 46 insertions, 26 deletions
diff --git a/malloc/mtrace.c b/malloc/mtrace.c
index a2facf6..2fda262 100644
--- a/malloc/mtrace.c
+++ b/malloc/mtrace.c
@@ -121,6 +121,41 @@ lock_and_info (const void *caller, Dl_info *mem)
return res;
}
+static void tr_freehook (void *, const void *);
+static void * tr_mallochook (size_t, const void *);
+static void * tr_reallochook (void *, size_t, const void *);
+static void * tr_memalignhook (size_t, size_t, const void *);
+
+/* Set all the default non-trace hooks. */
+static __always_inline void
+set_default_hooks (void)
+{
+ __free_hook = tr_old_free_hook;
+ __malloc_hook = tr_old_malloc_hook;
+ __realloc_hook = tr_old_realloc_hook;
+ __memalign_hook = tr_old_memalign_hook;
+}
+
+/* Set all of the tracing hooks used for mtrace. */
+static __always_inline void
+set_trace_hooks (void)
+{
+ __free_hook = tr_freehook;
+ __malloc_hook = tr_mallochook;
+ __realloc_hook = tr_reallochook;
+ __memalign_hook = tr_memalignhook;
+}
+
+/* Save the current set of hooks as the default hooks. */
+static __always_inline void
+save_default_hooks (void)
+{
+ tr_old_free_hook = __free_hook;
+ tr_old_malloc_hook = __malloc_hook;
+ tr_old_realloc_hook = __realloc_hook;
+ tr_old_memalign_hook = __memalign_hook;
+}
+
static void
tr_freehook (void *ptr, const void *caller)
{
@@ -138,12 +173,12 @@ tr_freehook (void *ptr, const void *caller)
tr_break ();
__libc_lock_lock (lock);
}
- __free_hook = tr_old_free_hook;
+ set_default_hooks ();
if (tr_old_free_hook != NULL)
(*tr_old_free_hook)(ptr, caller);
else
free (ptr);
- __free_hook = tr_freehook;
+ set_trace_hooks ();
__libc_lock_unlock (lock);
}
@@ -155,12 +190,12 @@ tr_mallochook (size_t size, const void *caller)
Dl_info mem;
Dl_info *info = lock_and_info (caller, &mem);
- __malloc_hook = tr_old_malloc_hook;
+ set_default_hooks ();
if (tr_old_malloc_hook != NULL)
hdr = (void *) (*tr_old_malloc_hook)(size, caller);
else
hdr = (void *) malloc (size);
- __malloc_hook = tr_mallochook;
+ set_trace_hooks ();
tr_where (caller, info);
/* We could be printing a NULL here; that's OK. */
@@ -185,16 +220,12 @@ tr_reallochook (void *ptr, size_t size, const void *caller)
Dl_info mem;
Dl_info *info = lock_and_info (caller, &mem);
- __free_hook = tr_old_free_hook;
- __malloc_hook = tr_old_malloc_hook;
- __realloc_hook = tr_old_realloc_hook;
+ set_default_hooks ();
if (tr_old_realloc_hook != NULL)
hdr = (void *) (*tr_old_realloc_hook)(ptr, size, caller);
else
hdr = (void *) realloc (ptr, size);
- __free_hook = tr_freehook;
- __malloc_hook = tr_mallochook;
- __realloc_hook = tr_reallochook;
+ set_trace_hooks ();
tr_where (caller, info);
if (hdr == NULL)
@@ -230,14 +261,12 @@ tr_memalignhook (size_t alignment, size_t size, const void *caller)
Dl_info mem;
Dl_info *info = lock_and_info (caller, &mem);
- __memalign_hook = tr_old_memalign_hook;
- __malloc_hook = tr_old_malloc_hook;
+ set_default_hooks ();
if (tr_old_memalign_hook != NULL)
hdr = (void *) (*tr_old_memalign_hook)(alignment, size, caller);
else
hdr = (void *) memalign (alignment, size);
- __memalign_hook = tr_memalignhook;
- __malloc_hook = tr_mallochook;
+ set_trace_hooks ();
tr_where (caller, info);
/* We could be printing a NULL here; that's OK. */
@@ -305,14 +334,8 @@ mtrace (void)
malloc_trace_buffer = mtb;
setvbuf (mallstream, malloc_trace_buffer, _IOFBF, TRACE_BUFFER_SIZE);
fprintf (mallstream, "= Start\n");
- tr_old_free_hook = __free_hook;
- __free_hook = tr_freehook;
- tr_old_malloc_hook = __malloc_hook;
- __malloc_hook = tr_mallochook;
- tr_old_realloc_hook = __realloc_hook;
- __realloc_hook = tr_reallochook;
- tr_old_memalign_hook = __memalign_hook;
- __memalign_hook = tr_memalignhook;
+ save_default_hooks ();
+ set_trace_hooks ();
#ifdef _LIBC
if (!added_atexit_handler)
{
@@ -338,10 +361,7 @@ muntrace (void)
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;
+ set_default_hooks ();
fprintf (f, "= End\n");
fclose (f);