Fix BZ #18084 -- backtrace (..., 0) dumps core on x86.

Other architectures also had bugs, or did unnecessary work.

ChangeLog

@@ -1,3 +1,16 @@
+2015-08-15  Paul Pluzhnikov  <ppluzhnikov@google.com>
+
+	[BZ #18084]
+	* debug/tst-backtrace2.c (do_test): Add test for BZ #18084.
+	* sysdeps/arm/backtrace.c (__backtrace): Handle size <= 0.
+	* sysdeps/i386/backtrace.c (__backtrace): Likewise.
+	* sysdeps/m68k/backtrace.c (__backtrace): Likewise.
+	* sysdeps/microblaze/backtrace.c (__backtrace): Likewise.
+	* sysdeps/s390/s390-32/backtrace.c (__backtrace): Likewise.
+	* sysdeps/s390/s390-64/backtrace.c (__backtrace): Likewise.
+	* sysdeps/sparc/backtrace.c (__backtrace): Likewise.
+	* sysdeps/x86_64/backtrace.c (__backtrace): Likewise.
+
 2015-08-15  Zack Weinberg  <zackw@panix.com>
 
 	[BZ #18795]

NEWS

@@ -9,9 +9,10 @@ Version 2.23
 
 * The following bugs are resolved with this release:
 
-  16517, 16519, 16520, 16734, 17905, 18086, 18265, 18480, 18525, 18618,
+  16517, 16519, 16520, 16734, 17905, 18084, 18086, 18265, 18480, 18525,
-  18647, 18661, 18674, 18778, 18781, 18787, 18789, 18790, 18795, 18820,
+  18618, 18647, 18661, 18674, 18778, 18781, 18787, 18789, 18790, 18795,
-  18824.
+  18820, 18824.
+
 
 Version 2.22
 

debug/tst-backtrace2.c

@@ -94,6 +94,12 @@ fn3 (void)
 NO_INLINE static int
 do_test (void)
 {
+  /* Test BZ #18084.  */
+  void *buffer[1];
+
+  if (backtrace (buffer, 0) != 0)
+    FAIL ();
+
   fn3 ();
   return ret;
 }

sysdeps/arm/backtrace.c

@@ -92,6 +92,10 @@ __backtrace (array, size)
      int size;
 {
   struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -100,8 +104,7 @@ __backtrace (array, size)
     return 0;
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
     --arg.cnt;

sysdeps/i386/backtrace.c

@@ -114,6 +114,10 @@ __backtrace (array, size)
      int size;
 {
   struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -122,8 +126,7 @@ __backtrace (array, size)
     return 0;
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
     --arg.cnt;

sysdeps/m68k/backtrace.c

@@ -111,6 +111,10 @@ int
 __backtrace (void **array, int size)
 {
   struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -119,8 +123,7 @@ __backtrace (void **array, int size)
     return 0;
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
     --arg.cnt;

sysdeps/microblaze/backtrace.c

@@ -114,6 +114,9 @@ __backtrace (void **array, int size)
   int count;
   int rc = 0;
 
+  if (size <= 0)
+    return 0;
+
   __asm__ __volatile__ ("mfs %0, rpc"
                         : "=r"(pc));
 

sysdeps/s390/s390-32/backtrace.c

@@ -126,6 +126,10 @@ int
 __backtrace (void **array, int size)
 {
   struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -135,8 +139,7 @@ __backtrace (void **array, int size)
     return __backchain_backtrace (array, size);
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   return arg.cnt != -1 ? arg.cnt : 0;
 }

sysdeps/s390/s390-64/backtrace.c

@@ -125,6 +125,10 @@ int
 __backtrace (void **array, int size)
 {
   struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -134,8 +138,7 @@ __backtrace (void **array, int size)
     return __backchain_backtrace (array, size);
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   return arg.cnt != -1 ? arg.cnt : 0;
 }

sysdeps/sparc/backtrace.c

@@ -108,7 +108,7 @@ __backtrace (void **array, int size)
   bool use_unwinder;
   int count;
 
-  if (!size)
+  if (size <= 0)
     return 0;
 
   use_unwinder = true;

sysdeps/x86_64/backtrace.c

@@ -97,6 +97,10 @@ __backtrace (array, size)
      int size;
 {
   struct trace_arg arg = { .array = array, .cfa = 0, .size = size, .cnt = -1 };
+
+  if (size <= 0)
+    return 0;
+
 #ifdef SHARED
   __libc_once_define (static, once);
 
@@ -105,8 +109,7 @@ __backtrace (array, size)
     return 0;
 #endif
 
-  if (size >= 1)
+  unwind_backtrace (backtrace_helper, &arg);
-    unwind_backtrace (backtrace_helper, &arg);
 
   /* _Unwind_Backtrace seems to put NULL address above
      _start.  Fix it up here.  */