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[Qemu-devel] [PATCH 15/81] 9pfs: local: truncate: don't follow symlinks
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 15/81] 9pfs: local: truncate: don't follow symlinks |
Date: |
Mon, 20 Mar 2017 18:07:39 -0500 |
From: Greg Kurz <address@hidden>
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>
(cherry picked from commit ac125d993b461d4dee4d6df4d93ac3f2eb959d1d)
Signed-off-by: Greg Kurz <address@hidden>
Signed-off-by: Michael Roth <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 80b3964..5e206e1 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -895,13 +895,14 @@ 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] [PATCH 00/81] Patch Round-up for stable 2.8.1, freeze on 2017-03-27, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 10/81] 9pfs: local: lremovexattr: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 11/81] 9pfs: local: unlinkat: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 09/81] 9pfs: local: lsetxattr: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 13/81] 9pfs: local: utimensat: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 14/81] 9pfs: local: statfs: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 15/81] 9pfs: local: truncate: don't follow symlinks,
Michael Roth <=
- [Qemu-devel] [PATCH 12/81] 9pfs: local: remove: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 19/81] 9pfs: local: rename: use renameat, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 17/81] 9pfs: local: lstat: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 16/81] 9pfs: local: readlink: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 21/81] 9pfs: local: link: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 18/81] 9pfs: local: renameat: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 29/81] 9pfs: fix bogus fd check in local_remove(), Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 25/81] 9pfs: local: mknod: don't follow symlinks, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 01/81] 9pfs: local: move xattr security ops to 9p-xattr.c, Michael Roth, 2017/03/20
- [Qemu-devel] [PATCH 20/81] 9pfs: local: improve error handling in link op, Michael Roth, 2017/03/20