Commit ab8a3e14 authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds

mbind(): fix leak of never putback pages

If mbind() receives an invalid address, do_mbind leaks a page.  The
following test program detects this leak.

This patch fixes it.

migrate_efault.c
=======================================
 #include <numaif.h>
 #include <numa.h>
 #include <sys/mman.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>

static unsigned long pagesize;

static void* make_hole_mapping(void)
{

	void* addr;

	addr = mmap(NULL, pagesize*3, PROT_READ|PROT_WRITE,
		    MAP_ANON|MAP_PRIVATE, 0, 0);
	if (addr == MAP_FAILED)
		return NULL;

	/* make page populate */
	memset(addr, 0, pagesize*3);

	/* make memory hole */
	munmap(addr+pagesize, pagesize);

	return addr;
}

int main(int argc, char** argv)
{
	void* addr;
	int ch;
	int node;
	struct bitmask *nmask = numa_allocate_nodemask();
	int err;
	int node_set = 0;

	while ((ch = getopt(argc, argv, "n:")) != -1){
		switch (ch){
		case 'n':
			node = strtol(optarg, NULL, 0);
			numa_bitmask_setbit(nmask, node);
			node_set = 1;
			break;
		default:
			;
		}
	}
	argc -= optind;
	argv += optind;

	if (!node_set)
		numa_bitmask_setbit(nmask, 0);

	pagesize = getpagesize();

	addr = make_hole_mapping();

	err = mbind(addr, pagesize*3, MPOL_BIND, nmask->maskp, nmask->size, MPOL_MF_MOVE_ALL);
	if (err)
		perror("mbind ");

	return 0;
}
=======================================
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 47f365eb
...@@ -1058,7 +1058,8 @@ static long do_mbind(unsigned long start, unsigned long len, ...@@ -1058,7 +1058,8 @@ static long do_mbind(unsigned long start, unsigned long len,
if (!err && nr_failed && (flags & MPOL_MF_STRICT)) if (!err && nr_failed && (flags & MPOL_MF_STRICT))
err = -EIO; err = -EIO;
} } else
putback_lru_pages(&pagelist);
up_write(&mm->mmap_sem); up_write(&mm->mmap_sem);
mpol_put(new); mpol_put(new);
......
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