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1 https://bugzilla.gnome.org/show_bug.cgi?id=697264 |
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2 https://git.gnome.org/browse/libxml2/commit/?id=5fe9e9ed1ccf217e11bd3cb99b1c6bb10cc96ba3 |
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3 |
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4 From 5fe9e9ed1ccf217e11bd3cb99b1c6bb10cc96ba3 Mon Sep 17 00:00:00 2001 |
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5 From: Daniel Veillard <[email protected]> |
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6 Date: Fri, 05 Apr 2013 15:10:41 +0000 |
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7 Subject: Remove risk of lockup in dictionary initialization |
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8 |
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9 Reported by Petr Sumbera <[email protected]> |
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10 Two threads entering xmlInitializeDict concurently could lead |
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11 to a lockup due to multiple initializations of the lock used. |
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12 To avoid this problem move this to a new private function |
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13 called from xmlOnceInit() and deprecate the old initalizer. |
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14 Since threaded programs must call xmlInitParser() and this |
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15 will lead to dereference of private data and the call to |
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16 xmlOnceInit() guaranteed to be unique this should be safe now. |
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17 --- |
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18 diff --git a/dict.c b/dict.c |
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19 index 164c7f2..5f71d55 100644 |
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20 --- a/dict.c |
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21 +++ b/dict.c |
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22 @@ -151,13 +151,28 @@ static unsigned int rand_seed = 0; |
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23 * xmlInitializeDict: |
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24 * |
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25 * Do the dictionary mutex initialization. |
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26 - * this function is not thread safe, initialization should |
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27 - * preferably be done once at startup |
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28 + * this function is deprecated |
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29 * |
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30 * Returns 0 if initialization was already done, and 1 if that |
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31 * call led to the initialization |
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32 */ |
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33 int xmlInitializeDict(void) { |
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34 + return(0); |
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35 +} |
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36 + |
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37 +/** |
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38 + * __xmlInitializeDict: |
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39 + * |
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40 + * This function is not public |
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41 + * Do the dictionary mutex initialization. |
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42 + * this function is not thread safe, initialization should |
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43 + * normally be done once at setup when called from xmlOnceInit() |
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44 + * we may also land in this code if thread support is not compiled in |
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45 + * |
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46 + * Returns 0 if initialization was already done, and 1 if that |
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47 + * call led to the initialization |
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48 + */ |
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49 +int __xmlInitializeDict(void) { |
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50 if (xmlDictInitialized) |
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51 return(1); |
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52 |
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53 @@ -183,7 +198,7 @@ int __xmlRandom(void) { |
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54 int ret; |
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55 |
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56 if (xmlDictInitialized == 0) |
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57 - xmlInitializeDict(); |
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58 + __xmlInitializeDict(); |
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59 |
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60 xmlRMutexLock(xmlDictMutex); |
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61 #ifdef HAVE_RAND_R |
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62 @@ -522,7 +537,7 @@ xmlDictCreate(void) { |
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63 xmlDictPtr dict; |
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64 |
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65 if (!xmlDictInitialized) |
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66 - if (!xmlInitializeDict()) |
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67 + if (!__xmlInitializeDict()) |
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68 return(NULL); |
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69 |
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70 #ifdef DICT_DEBUG_PATTERNS |
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71 @@ -590,7 +605,7 @@ xmlDictCreateSub(xmlDictPtr sub) { |
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72 int |
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73 xmlDictReference(xmlDictPtr dict) { |
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74 if (!xmlDictInitialized) |
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75 - if (!xmlInitializeDict()) |
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76 + if (!__xmlInitializeDict()) |
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77 return(-1); |
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78 |
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79 if (dict == NULL) return -1; |
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80 @@ -754,7 +769,7 @@ xmlDictFree(xmlDictPtr dict) { |
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81 return; |
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82 |
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83 if (!xmlDictInitialized) |
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84 - if (!xmlInitializeDict()) |
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85 + if (!__xmlInitializeDict()) |
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86 return; |
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87 |
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88 /* decrement the counter, it may be shared by a parser and docs */ |
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89 diff --git a/libxml.h b/libxml.h |
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90 index 7558b5f..2da9044 100644 |
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91 --- a/libxml.h |
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92 +++ b/libxml.h |
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93 @@ -84,6 +84,8 @@ void __xmlGlobalInitMutexLock(void); |
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94 void __xmlGlobalInitMutexUnlock(void); |
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95 void __xmlGlobalInitMutexDestroy(void); |
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96 |
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97 +int __xmlInitializeDict(void); |
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98 + |
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99 #if defined(HAVE_RAND) && defined(HAVE_SRAND) && defined(HAVE_TIME) |
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100 /* |
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101 * internal thread safe random function |
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102 diff --git a/threads.c b/threads.c |
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103 index c8414e1..f2f2703 100644 |
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104 --- a/threads.c |
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105 +++ b/threads.c |
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106 @@ -954,6 +954,7 @@ xmlOnceInit(void) |
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107 #ifdef HAVE_PTHREAD_H |
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108 (void) pthread_key_create(&globalkey, xmlFreeGlobalState); |
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109 mainthread = pthread_self(); |
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110 + __xmlInitializeDict(); |
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111 #elif defined(HAVE_WIN32_THREADS) |
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112 if (!run_once.done) { |
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113 if (InterlockedIncrement(&run_once.control) == 1) { |
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114 @@ -961,6 +962,7 @@ xmlOnceInit(void) |
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115 globalkey = TlsAlloc(); |
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116 #endif |
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117 mainthread = GetCurrentThreadId(); |
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118 + __xmlInitializeDict(); |
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119 run_once.done = 1; |
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120 } else { |
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121 /* Another thread is working; give up our slice and |
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122 @@ -974,6 +976,7 @@ xmlOnceInit(void) |
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123 globalkey = tls_allocate(); |
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124 tls_set(globalkey, NULL); |
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125 mainthread = find_thread(NULL); |
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126 + __xmlInitializeDict(); |
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127 } else |
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128 atomic_add(&run_once_init, -1); |
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129 #endif |
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130 -- |
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131 cgit v0.9.1 |