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 08:48:02 +0100 |
| commit | 47693835edb13750dff59f82224f606e19cef294 (patch) | |
| tree | 39ad52d471cd6e73bc0ae434e07ecc153d4735f0 | |
| parent | 36b98806d243f3d38b51fb429d2303c5b67ffc2b (diff) | |
| download | linux-47693835edb13750dff59f82224f606e19cef294.tar.gz linux-47693835edb13750dff59f82224f606e19cef294.tar.bz2 linux-47693835edb13750dff59f82224f606e19cef294.zip | |
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 692ae2e2f8cc..c9fd598b0325 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -7576,7 +7576,7 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *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; } |