linux-kernel - [PATCH 3.2 074/102] shmem: fix nlink for rename overwrite directory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1414880883.876822152@decadent.org.uk>
Date:	Sat, 01 Nov 2014 22:28:03 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Al Viro" <viro@...iv.linux.org.uk>,
	"Miklos Szeredi" <mszeredi@...e.cz>
Subject: [PATCH 3.2 074/102] shmem: fix nlink for rename overwrite directory

3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@...e.cz>

commit b928095b0a7cff7fb9fcf4c706348ceb8ab2c295 upstream.

If overwriting an empty directory with rename, then need to drop the extra
nlink.

Test prog:

#include <stdio.h>
#include <fcntl.h>
#include <err.h>
#include <sys/stat.h>

int main(void)
{
	const char *test_dir1 = "test-dir1";
	const char *test_dir2 = "test-dir2";
	int res;
	int fd;
	struct stat statbuf;

	res = mkdir(test_dir1, 0777);
	if (res == -1)
		err(1, "mkdir(\"%s\")", test_dir1);

	res = mkdir(test_dir2, 0777);
	if (res == -1)
		err(1, "mkdir(\"%s\")", test_dir2);

	fd = open(test_dir2, O_RDONLY);
	if (fd == -1)
		err(1, "open(\"%s\")", test_dir2);

	res = rename(test_dir1, test_dir2);
	if (res == -1)
		err(1, "rename(\"%s\", \"%s\")", test_dir1, test_dir2);

	res = fstat(fd, &statbuf);
	if (res == -1)
		err(1, "fstat(%i)", fd);

	if (statbuf.st_nlink != 0) {
		fprintf(stderr, "nlink is %lu, should be 0\n", statbuf.st_nlink);
		return 1;
	}

	return 0;
}

Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 mm/shmem.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1719,8 +1719,10 @@ static int shmem_rename(struct inode *ol
 
 	if (new_dentry->d_inode) {
 		(void) shmem_unlink(new_dir, new_dentry);
-		if (they_are_dirs)
+		if (they_are_dirs) {
+			drop_nlink(new_dentry->d_inode);
 			drop_nlink(old_dir);
+		}
 	} else if (they_are_dirs) {
 		drop_nlink(old_dir);
 		inc_nlink(new_dir);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/