[PATCH] fs: Fix file create bug when parent is not a directory

[Sascha Hauer]

When creating a file or a directory we have to check if the parent
is actually a directory. Otherwise trying it results in a crash.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 fs/fs.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/fs/fs.c b/fs/fs.c
index af73c8c..6d5740b 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -33,6 +33,7 @@
 #include <libbb.h>
 #include <magicvar.h>
 #include <environment.h>
+#include <libgen.h>
 
 void *read_file(const char *filename, size_t *size)
 {
@@ -427,6 +428,25 @@ out:
 	return ret;
 }
 
+static int parent_check_directory(const char *path)
+{
+	struct stat s;
+	int ret;
+	char *dir = dirname(xstrdup(path));
+
+	ret = stat(dir, &s);
+
+	free(dir);
+
+	if (ret)
+		return -ENOENT;
+
+	if (!S_ISDIR(s.st_mode))
+		return -ENOTDIR;
+
+	return 0;
+}
+
 const char *getcwd(void)
 {
 	return cwd;
@@ -515,6 +535,12 @@ int open(const char *pathname, int flags, ...)
 		goto out1;
 	}
 
+	if (exist_err) {
+		ret = parent_check_directory(path);
+		if (ret)
+			goto out1;
+	}
+
 	f = get_file();
 	if (!f) {
 		ret = -EMFILE;
@@ -1153,6 +1179,10 @@ int mkdir (const char *pathname, mode_t mode)
 	char *freep = p;
 	int ret;
 
+	ret = parent_check_directory(p);
+	if (ret)
+		goto out;
+
 	ret = path_check_prereq(pathname, S_UB_DOES_NOT_EXIST);
 	if (ret)
 		goto out;
-- 
1.7.10