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[Qemu-devel] [PATCH 16/29] 9pfs: local: truncate: don't follow symlinks
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH 16/29] 9pfs: local: truncate: don't follow symlinks |
Date: |
Mon, 20 Feb 2017 15:41:24 +0100 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
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>
---
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 ebc12f3c0691..da233198d032 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -888,13 +888,14 @@ 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;
}
- [Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symlinks, (continued)
- [Qemu-devel] [PATCH 11/29] 9pfs: local: lremovexattr: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 12/29] 9pfs: local: unlinkat: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 13/29] 9pfs: local: remove: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 14/29] 9pfs: local: utimensat: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 15/29] 9pfs: local: statfs: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 16/29] 9pfs: local: truncate: don't follow symlinks,
Greg Kurz <=
- [Qemu-devel] [PATCH 17/29] 9pfs: local: readlink: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 18/29] 9pfs: local: lstat: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 19/29] 9pfs: local: renameat: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 20/29] 9pfs: local: rename: use renameat, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 21/29] 9pfs: local: improve error handling in link op, Greg Kurz, 2017/02/20