proc: fix /proc/*/map_files lookup some more

I totally forgot that _parse_integer() accepts arbitrary amount of
leading zeroes leading to the following lookups:

		OK
	# readlink /proc/1/map_files/56427ecba000-56427eddc000
	/lib/systemd/systemd

		bogus
	# readlink /proc/1/map_files/00000000000056427ecba000-56427eddc000
	/lib/systemd/systemd
	# readlink /proc/1/map_files/56427ecba000-00000000000056427eddc000
	/lib/systemd/systemd

Link: http://lkml.kernel.org/r/20180303215130.GA23480@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/tools/testing/selftests/proc/proc-self-map-files-002.c b/tools/testing/selftests/proc/proc-self-map-files-002.c
new file mode 100644
index 000000000000..aebf4be56111
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-self-map-files-002.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright _ 2018 Alexey Dobriyan <adobriyan@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+/* Test readlink /proc/self/map_files/... with address 0. */
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+
+static void pass(const char *fmt, unsigned long a, unsigned long b)
+{
+	char name[64];
+	char buf[64];
+
+	snprintf(name, sizeof(name), fmt, a, b);
+	if (readlink(name, buf, sizeof(buf)) == -1)
+		exit(1);
+}
+
+static void fail(const char *fmt, unsigned long a, unsigned long b)
+{
+	char name[64];
+	char buf[64];
+
+	snprintf(name, sizeof(name), fmt, a, b);
+	if (readlink(name, buf, sizeof(buf)) == -1 && errno == ENOENT)
+		return;
+	exit(1);
+}
+
+int main(void)
+{
+	const unsigned int PAGE_SIZE = sysconf(_SC_PAGESIZE);
+	void *p;
+	int fd;
+	unsigned long a, b;
+
+	fd = open("/dev/zero", O_RDONLY);
+	if (fd == -1)
+		return 1;
+
+	p = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE|MAP_FIXED, fd, 0);
+	if (p == MAP_FAILED) {
+		if (errno == EPERM)
+			return 2;
+		return 1;
+	}
+
+	a = (unsigned long)p;
+	b = (unsigned long)p + PAGE_SIZE;
+
+	pass("/proc/self/map_files/%lx-%lx", a, b);
+	fail("/proc/self/map_files/ %lx-%lx", a, b);
+	fail("/proc/self/map_files/%lx -%lx", a, b);
+	fail("/proc/self/map_files/%lx- %lx", a, b);
+	fail("/proc/self/map_files/%lx-%lx ", a, b);
+	fail("/proc/self/map_files/0%lx-%lx", a, b);
+	fail("/proc/self/map_files/%lx-0%lx", a, b);
+	if (sizeof(long) == 4) {
+		fail("/proc/self/map_files/100000000%lx-%lx", a, b);
+		fail("/proc/self/map_files/%lx-100000000%lx", a, b);
+	} else if (sizeof(long) == 8) {
+		fail("/proc/self/map_files/10000000000000000%lx-%lx", a, b);
+		fail("/proc/self/map_files/%lx-10000000000000000%lx", a, b);
+	} else
+		return 1;
+
+	return 0;
+}