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      1 /*
      2  * Copyright (c) 2015 Dmitry V. Levin <ldv (at) altlinux.org>
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. The name of the author may not be used to endorse or promote products
     14  *    derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifdef HAVE_CONFIG_H
     29 # include "config.h"
     30 #endif
     31 #include <dlfcn.h>
     32 #include <fcntl.h>
     33 #include <unistd.h>
     34 #include <sys/mman.h>
     35 #include <sys/wait.h>
     36 #include <sys/sendfile.h>
     37 
     38 int main(void)
     39 {
     40 	const unsigned long pagesize = sysconf(_SC_PAGESIZE);
     41 
     42 #ifdef __s390__
     43 	/*
     44 	 * The si_addr field is unreliable:
     45 	 * https://marc.info/?l=linux-s390&m=142515870124248&w=2
     46 	 */
     47 	return 77;
     48 #endif
     49 
     50 	/* write instruction pointer length to the log */
     51 	if (write(-1, NULL, 2 * sizeof(void *)) >= 0)
     52 		return 77;
     53 
     54 	/* just a noticeable line in the log */
     55 	if (munmap(&main, 0) >= 0)
     56 		return 77;
     57 
     58 	int pid = fork();
     59 	if (pid < 0)
     60 		return 77;
     61 
     62 	if (!pid) {
     63 		const unsigned long mask = ~(pagesize - 1);
     64 		unsigned long addr = (unsigned long) &main & mask;
     65 		unsigned long size = pagesize << 1;
     66 
     67 #ifdef HAVE_DLADDR
     68 		Dl_info info;
     69 		if (dladdr(&main, &info)) {
     70 			const unsigned long base =
     71 				(unsigned long) info.dli_fbase & mask;
     72 			if (base < addr) {
     73 				size += addr - base;
     74 				addr = base;
     75 			}
     76 		} else
     77 #endif
     78 		{
     79 			addr -= size;
     80 			size <<= 1;
     81 		}
     82 
     83 		/* SIGSEGV is expected */
     84 		(void) munmap((void *) addr, size);
     85 		(void) munmap((void *) addr, size);
     86 		return 77;
     87 	}
     88 
     89 	int status;
     90 	if (wait(&status) != pid ||
     91 	    !WIFSIGNALED(status) ||
     92 	    WTERMSIG(status) != SIGSEGV)
     93 		return 77;
     94 
     95 	/* dump process map for debug purposes */
     96 	close(0);
     97 	if (!open("/proc/self/maps", O_RDONLY))
     98 		(void) sendfile(1, 0, NULL, pagesize);
     99 
    100 	return 0;
    101 }
    102