diff options
| author | Jann Horn <jannh@google.com> | 2023-11-24 17:48:31 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-08 08:42:00 +0100 |
| commit | b93441c3125c6bc12914c01a61f469285bc506b1 (patch) | |
| tree | d1672ae476f060ad855b7884e47b9e69096c005c | |
| parent | 2590e30370a07a9c9f679bf9d8ab0b9e533695a9 (diff) | |
btrfs: send: ensure send_fd is writable
commit 0ac1d13a55eb37d398b63e6ff6db4a09a2c9128c upstream.
kernel_write() requires the caller to ensure that the file is writable.
Let's do that directly after looking up the ->send_fd.
We don't need a separate bailout path because the "out" path already
does fput() if ->send_filp is non-NULL.
This has no security impact for two reasons:
- the ioctl requires CAP_SYS_ADMIN
- __kernel_write() bails out on read-only files - but only since 5.8,
see commit a01ac27be472 ("fs: check FMODE_WRITE in __kernel_write")
Reported-and-tested-by: syzbot+12e098239d20385264d3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=12e098239d20385264d3
Fixes: 31db9f7c23fb ("Btrfs: introduce BTRFS_IOC_SEND for btrfs send/receive")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/btrfs/send.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index b08e7fcd8c34..f2cb7fec7547 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6680,7 +6680,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) sctx->flags = arg->flags; sctx->send_filp = fget(arg->send_fd); - if (!sctx->send_filp) { + if (!sctx->send_filp || !(sctx->send_filp->f_mode & FMODE_WRITE)) { ret = -EBADF; goto out; } |