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// setattr.c by kanda.motohiro@gmail.com
// xfs extended attribute corruption bug reproducer
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/xattr.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <linux/limits.h>
#define die() do { perror(""); \
fprintf(stderr, "error at line %d\n", __LINE__); \
exit(1); } while (0)
#define fail(...) do { \
fprintf(stderr, __VA_ARGS__); exit (1); \
} while (0)
void usage(char *progname)
{
fail("usage: %s [-m max_attr_size] <file>\n", progname);
}
int main(int argc, char *argv[])
{
int ret;
int fd;
int c;
char *path;
char *name = "user.world";
char *value;
struct stat sbuf;
size_t size = sizeof(value);
size_t maxsize = XATTR_SIZE_MAX;
while ((c = getopt(argc, argv, "m:")) != -1) {
char *endp;
switch (c) {
case 'm':
maxsize = strtoul(optarg, &endp, 0);
if (*endp || (maxsize > XATTR_SIZE_MAX))
fail("Invalid 'max_attr_size' value\n");
break;
default:
usage(argv[0]);
}
}
if (optind == argc - 1)
path = argv[optind];
else
usage(argv[0]);
fd = open(path, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (fd < 0) die();
/*
* The value should be 3/4 the size of a fs block to ensure that we
* get to extents format.
*/
ret = fstat(fd, &sbuf);
if (ret < 0) die();
size = sbuf.st_blksize * 3 / 4;
if (!size)
fail("Invalid st_blksize(%ld)\n", sbuf.st_blksize);
size = MIN(size, maxsize);
value = malloc(size);
if (!value)
fail("Failed to allocate memory\n");
/* First, create a small xattr. */
memset(value, '0', 1);
ret = fsetxattr(fd, name, value, 1, XATTR_CREATE);
if (ret < 0) die();
close(fd);
fd = open(path, O_RDWR);
if (fd < 0) die();
/* Then, replace it with bigger one, forcing short form to leaf conversion. */
memset(value, '1', size);
ret = fsetxattr(fd, name, value, size, XATTR_REPLACE);
if (ret < 0) die();
close(fd);
return 0;
}
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