This is a note to let you know that I've just added the patch titled
CIFS: fix type confusion in copy offload ioctl
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-fix-type-confusion-in-copy-offload-ioctl.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4c17a6d56bb0cad3066a714e94f7185a24b40f49 Mon Sep 17 00:00:00 2001
From: Jann Horn <jann@xxxxxxxxx>
Date: Fri, 11 Sep 2015 16:27:27 +0200
Subject: CIFS: fix type confusion in copy offload ioctl
From: Jann Horn <jann@xxxxxxxxx>
commit 4c17a6d56bb0cad3066a714e94f7185a24b40f49 upstream.
This might lead to local privilege escalation (code execution as
kernel) for systems where the following conditions are met:
- CONFIG_CIFS_SMB2 and CONFIG_CIFS_POSIX are enabled
- a cifs filesystem is mounted where:
- the mount option "vers" was used and set to a value >=2.0
- the attacker has write access to at least one file on the filesystem
To attack this, an attacker would have to guess the target_tcon
pointer (but guessing wrong doesn't cause a crash, it just returns an
error code) and win a narrow race.
Signed-off-by: Jann Horn <jann@xxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/ioctl.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -70,6 +70,12 @@ static long cifs_ioctl_clone(unsigned in
goto out_drop_write;
}
+ if (src_file.file->f_op->unlocked_ioctl != cifs_ioctl) {
+ rc = -EBADF;
+ cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
+ goto out_fput;
+ }
+
if ((!src_file.file->private_data) || (!dst_file->private_data)) {
rc = -EBADF;
cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");
Patches currently in stable-queue which might be from jann@xxxxxxxxx are
queue-4.2/cifs-fix-type-confusion-in-copy-offload-ioctl.patch
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