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[Qemu-devel] [PULL 18/31] 9pfs: local: truncate: don't follow symlinks
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PULL 18/31] 9pfs: local: truncate: don't follow symlinks |
Date: |
Tue, 28 Feb 2017 00:00:08 +0100 |
The local_truncate() callback is vulnerable to symlink attacks because
it calls truncate() which follows symbolic links in all path elements.
This patch converts local_truncate() to rely on open_nofollow() and
ftruncate() instead.
This partly fixes CVE-2016-9602.
Signed-off-by: Greg Kurz <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
hw/9pfs/9p-local.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index ae5d26821791..c6c114839287 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -894,13 +894,14 @@ err_out:
static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
{
- char *buffer;
- int ret;
- char *path = fs_path->data;
+ int fd, ret;
- buffer = rpath(ctx, path);
- ret = truncate(buffer, size);
- g_free(buffer);
+ fd = local_open_nofollow(ctx, fs_path->data, O_WRONLY, 0);
+ if (fd == -1) {
+ return -1;
+ }
+ ret = ftruncate(fd, size);
+ close_preserve_errno(fd);
return ret;
}
--
2.7.4
- [Qemu-devel] [PULL 03/31] throttle: factor out duplicate code, (continued)
- [Qemu-devel] [PULL 03/31] throttle: factor out duplicate code, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 21/31] 9pfs: local: renameat: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 16/31] 9pfs: local: utimensat: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 04/31] 9pfs: local: move xattr security ops to 9p-xattr.c, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 14/31] 9pfs: local: unlinkat: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 17/31] 9pfs: local: statfs: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 19/31] 9pfs: local: readlink: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 20/31] 9pfs: local: lstat: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 23/31] 9pfs: local: improve error handling in link op, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 26/31] 9pfs: local: chown: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 18/31] 9pfs: local: truncate: don't follow symlinks,
Greg Kurz <=
- [Qemu-devel] [PULL 22/31] 9pfs: local: rename: use renameat, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 09/31] 9pfs: local: open/opendir: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 30/31] 9pfs: local: open2: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 29/31] 9pfs: local: mkdir: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 31/31] 9pfs: local: drop unused code, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 28/31] 9pfs: local: mknod: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 24/31] 9pfs: local: link: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 27/31] 9pfs: local: symlink: don't follow symlinks, Greg Kurz, 2017/02/27
- [Qemu-devel] [PULL 25/31] 9pfs: local: chmod: don't follow symlinks, Greg Kurz, 2017/02/27
- Re: [Qemu-devel] [PULL 00/31] 9p patches 2017-02-27 for 2.9 soft freeze, no-reply, 2017/02/27