<分区>
我有一个小代码，它在堆上分配一些内存，然后在使用后尝试释放它。 我在使用内存映射时遇到此错误。
代码是::
void merge(int *arr, int start, int mid, int end)
{
int i = 0, j = 0, k = 0, tmp1 = 0, siz = 0;
int *pt = NULL;
j = start, k = mid+1, tmp1 = start;
siz = (end - start) + 1;
if ((pt = malloc(siz * sizeof(int))) == NULL) /* line 32 */
{
printf("\n ERROR Aloocating mem \n");
return;
}
while (j <= mid && k <= end)
{
if (arr[j] <= arr[k])
{
pt[tmp1] = arr[j];
++j;
++tmp1;
}
if (arr[j] > arr[k])
{
pt[tmp1] = arr[k]; /* line 48 */
++k;
++tmp1;
}
}
while (j <= mid)
{
pt[tmp1] = arr[j]; /* line 56 */
++tmp1;
++j;
}
while (k <= end)
{
pt[tmp1] = arr[k];
++k;
++tmp1;
}
for (i = 0; i < siz; i++)
{
arr[end] = pt[end]; /* line 69 */
--end;
}
free(pt);
}
我得到的错误是::
*** glibc detected *** ./m: free(): invalid next size (fast): 0x0940c008 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6(+0x6b161)[0x213161]
/lib/tls/i686/cmov/libc.so.6(+0x6c9b8)[0x2149b8]
/lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0x217a9d]
./m[0x80486d8]
./m[0x8048562]
./m[0x8048526]
./m[0x8048542]
./m[0x804874b]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0x1bebd6]
./m[0x8048441]
======= Memory map: ========
001a8000-002fb000 r-xp 00000000 08:01 1535 /lib/tls/i686/cmov/libc-2.11.1.so
002fb000-002fd000 r--p 00153000 08:01 1535 /lib/tls/i686/cmov/libc-2.11.1.so
002fd000-002fe000 rw-p 00155000 08:01 1535 /lib/tls/i686/cmov/libc-2.11.1.so
002fe000-00301000 rw-p 00000000 00:00 0
00483000-0049e000 r-xp 00000000 08:01 1712996 /lib/ld-2.11.1.so
0049e000-0049f000 r--p 0001a000 08:01 1712996 /lib/ld-2.11.1.so
0049f000-004a0000 rw-p 0001b000 08:01 1712996 /lib/ld-2.11.1.so
007f8000-00815000 r-xp 00000000 08:01 1708381 /lib/libgcc_s.so.1
00815000-00816000 r--p 0001c000 08:01 1708381 /lib/libgcc_s.so.1
00816000-00817000 rw-p 0001d000 08:01 1708381 /lib/libgcc_s.so.1
00b38000-00b39000 r-xp 00000000 00:00 0 [vdso]
08048000-08049000 r-xp 00000000 08:01 1317230 /home/abhi/Desktop/ad/A1/misc/m
08049000-0804a000 r--p 00000000 08:01 1317230 /home/abhi/Desktop/ad/A1/misc/m
0804a000-0804b000 rw-p 00001000 08:01 1317230 /home/abhi/Desktop/ad/A1/misc/m
0940c000-0942d000 rw-p 00000000 00:00 0 [heap]
b7600000-b7621000 rw-p 00000000 00:00 0
b7621000-b7700000 ---p 00000000 00:00 0
b777e000-b777f000 rw-p 00000000 00:00 0
b778c000-b7790000 rw-p 00000000 00:00 0
bf8b5000-bf8ca000 rw-p 00000000 00:00 0 [stack]
Aborted
查看了SO上一些类似问题的答案，得知是内存错误。
所以我用 valgrind 运行编码并得到以下输出(不是完整的输出)
==4494==
==4494== Invalid write of size 4
==4494== at 0x8048650: merge (merge.c:48)
==4494== by 0x8048561: merge_sort (merge.c:20)
==4494== by 0x8048525: merge_sort (merge.c:18)
==4494== by 0x8048541: merge_sort (merge.c:19)
==4494== by 0x8048766: main (merge.c:89)
==4494== Address 0x41920ac is 4 bytes after a block of size 8 alloc'd
==4494== at 0x4023AB8: malloc (vg_replace_malloc.c:207)
==4494== by 0x80485CB: merge (merge.c:32)
==4494== by 0x8048561: merge_sort (merge.c:20)
==4494== by 0x8048525: merge_sort (merge.c:18)
==4494== by 0x8048541: merge_sort (merge.c:19)
==4494== by 0x8048766: main (merge.c:89)
==4494==
==4494== Invalid write of size 4
==4494== at 0x8048680: merge (merge.c:56)
==4494== by 0x8048561: merge_sort (merge.c:20)
==4494== by 0x8048525: merge_sort (merge.c:18)
==4494== by 0x8048541: merge_sort (merge.c:19)
==4494== by 0x8048766: main (merge.c:89)
==4494== Address 0x41920b0 is 8 bytes after a block of size 8 alloc'd
==4494== at 0x4023AB8: malloc (vg_replace_malloc.c:207)
==4494== Invalid read of size 4
==4494== at 0x80486D5: merge (merge.c:69)
==4494== by 0x8048561: merge_sort (merge.c:20)
==4494== by 0x8048541: merge_sort (merge.c:19)
==4494== by 0x8048766: main (merge.c:89)
==4494== Address 0x41920ec is 8 bytes after a block of size 12 alloc'd
==4494== at 0x4023AB8: malloc (vg_replace_malloc.c:207)
==4494== by 0x80485CB: merge (merge.c:32)
==4494== by 0x8048561: merge_sort (merge.c:20)
==4494== by 0x8048541: merge_sort (merge.c:19)
==4494== by 0x8048766: main (merge.c:89)
我无法纠正 malloc 对我来说看起来不错的问题。我正在分配 siz * sizeof(int) 字节(int 在我的机器上是 4 个字节)，然后以数组形式使用分配的内存。
如果有人指出我正在做的错误并解释原因，将不胜感激。 谢谢