Hi,
Has anyone noticed that you can easily provoke a kernel panic just by
invoking the F_LOG2PHYS fcntl on any file residing on a MacFUSE mount?
Steps to reproduce:
- Mount a volume with your favorite MacFUSE driver (loopback.c is always
a good one).
- Compile and run the included demo utility, log2phys.c, for any file on
the MacFUSE mount.
- Voila, kernel panic. (Confirmed on Leopard and Snow Leopard with
MacFUSE 2.0.3.)
Regards,
- Erik
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/**
* log2phys - Simple command line wrapper for the F_LOG2PHYS fcntl.
*
* Copyright (C) 2009 Erik Larsson, Tuxera Ltd.
*
* License: Do whatever you want. Just don't sue me. :)
*/
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <libgen.h>
static void print_usage(char *invoke_cmd, FILE *out_stream) {
fprintf(out_stream, "usage: %s <filename> [<offset>]\n",
basename(invoke_cmd));
}
static int report_error(const char *message, int errno_value) {
fprintf(stderr, "ERROR: %s (errno: %d / \"%s\")\n",
message, errno_value, strerror(errno_value));
return 1;
}
int main(int argc, char **argv) {
if(argc < 2 || argc > 3) {
print_usage(argv[0], stderr);
return 1;
}
else {
char *file = argv[1];
unsigned long long logical_offset = 0;
if(argc == 3) {
if(sscanf(argv[2], "%llu", &logical_offset) != 1) {
fprintf(stderr, "Invalid offset: %s\n", argv[2]);
print_usage(argv[0], stderr);
return 1;
}
}
int fd = open(file, O_RDONLY);
if(fd == -1)
return report_error("Failed to open file.", errno);
if(lseek(fd, logical_offset, SEEK_SET) == -1)
return report_error("Failed to seek to desired offset.", errno);
struct log2phys data = {};
if(fcntl(fd, F_LOG2PHYS, &data) == -1)
return report_error("fcntl F_LOG2PHYS failed.", errno);
printf("%lld\n", (long long) data.l2p_devoffset);
if(close(fd) == -1)
return report_error("Failed to close file.", errno);
return 0;
}
}
