Attachment 727627 Details for Bug 1039348

test program to test stack guard page behavior

stack_crash.c (text/x-c), 2.05 KB, created by Michal Hocko on 2017-06-05 06:52:12 UTC

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Creator: Michal Hocko

Created: 2017-06-05 06:52:12 UTC

Size: 2.05 KB

patch

obsolete

>#include <sys/mman.h>
>#include <stdio.h>
>#include <unistd.h>
>#include <alloca.h>
>#include <signal.h>
>#include <stdlib.h>
>
>#define PAGE_SHIFT              12
>#define PAGE_SIZE               (1UL << PAGE_SHIFT)
>#define PAGE_MASK (~(PAGE_SIZE-1))
>#define GAP (20UL<<20)
>#define SIGNAL_STACK_SIZE (1UL<<20)
>
>void recurse(void)
>{
>	void * ptr = alloca(10);
>	recurse();
>}
>
>#define MAPPED_LEN PAGE_SIZE
>static unsigned long mapped_addr;
>void segv_handler(int sig, siginfo_t *info, void *data)
>{
>	if (sig == SIGSEGV) {
>		unsigned long addr = (unsigned long)info->si_addr;
>		unsigned long mmap_end = mapped_addr + MAPPED_LEN;
>		unsigned long diff;
>		char cmd[128];
>
>#ifndef CONFIG_STACK_GROWSUP
>		diff = addr - mmap_end;
>#else
>		diff = mmap_addr - addr;
>#endif
>		printf("address:0x%lx aligned:0x%lx mapped:[%lx,%lx] diff:%lu\n", addr, addr & PAGE_MASK, mapped_addr, mapped_addr+PAGE_SIZE, diff);	
>		snprintf(cmd, sizeof(cmd) - 1, "cat /proc/%d/smaps | grep -A5 -B21 -A20 '\\[stack\\]'", getpid());
>		system(cmd);
>		abort();
>	}
>}
>
>int main()
>{
>	void *addr;
>	stack_t signal_stack;
>	struct sigaction segv_sig = {.sa_sigaction = segv_handler, .sa_flags = SA_ONSTACK|SA_SIGINFO};
>	int stack_top;
>	unsigned long stack_addr = (unsigned long)&stack_top;
>
>#ifndef CONFIG_STACK_GROWSUP
>	mapped_addr = stack_addr-GAP;
>#else
>	mapped_addr = stack_addr+GAP;
>#endif
>	mapped_addr &= PAGE_MASK;
>	addr = mmap((void *)mapped_addr, MAPPED_LEN,
>			PROT_READ|PROT_WRITE,
>			MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
>	if (addr == MAP_FAILED) {
>		perror("mmap:");
>		return 1;
>	}
>	printf("Stack top:0x%lx mmap:0x%lx\n", stack_addr, mapped_addr);
>
>	/* Make sure that our SEGV handler will have a stack to run on */
>	signal_stack.ss_sp = malloc(SIGNAL_STACK_SIZE);
>	if (!signal_stack.ss_sp) {
>		perror("alternate stack allocation");
>		return 1;
>	}
>	signal_stack.ss_size = SIGNAL_STACK_SIZE;
>	signal_stack.ss_flags = 0;
>	if (sigaltstack(&signal_stack, NULL) == -1) {
>		perror("sigaltstack");
>		return 1;
>	}
>	sigaction(SIGSEGV, &segv_sig, NULL);
>	/*
>	mlockall(MCL_CURRENT|MCL_FUTURE);
>	*/
>
>	recurse();
>	/* Should never return */
>	return 1;
>}

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Attachments on bug 1039348: 725338 | 727600 | 727601 | 727627 | 727764 | 727765 | 729853