diff options
authorSteve French <smfrench@gmail.com>2018-04-20 12:19:07 -0500
committerSteve French <smfrench@gmail.com>2018-04-20 13:31:32 -0500
commit1d0cffa674cfa7d185a302c8c6850fc50b893bed (patch)
parentff30b89e0ab71115cbad6ae10a58bd83fe18b41f (diff)
cifs: do not allow creating sockets except with SMB1 posix exensions
RHBZ: 1453123 Since at least the 3.10 kernel and likely a lot earlier we have not been able to create unix domain sockets in a cifs share when mounted using the SFU mount option (except when mounted with the cifs unix extensions to Samba e.g.) Trying to create a socket, for example using the af_unix command from xfstests will cause : BUG: unable to handle kernel NULL pointer dereference at 00000000 00000040 Since no one uses or depends on being able to create unix domains sockets on a cifs share the easiest fix to stop this vulnerability is to simply not allow creation of any other special files than char or block devices when sfu is used. Added update to Ronnie's patch to handle a tcon link leak, and to address a buf leak noticed by Gustavo and Colin. Acked-by: Gustavo A. R. Silva <gustavo@embeddedor.com> CC: Colin Ian King <colin.king@canonical.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reported-by: Eryu Guan <eguan@redhat.com> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Cc: stable@vger.kernel.org
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 81ba6e0d88d8..925844343038 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -684,6 +684,9 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode,
goto mknod_out;
+ if (!S_ISCHR(mode) && !S_ISBLK(mode))
+ goto mknod_out;
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
goto mknod_out;
@@ -692,10 +695,8 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode,
buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
if (buf == NULL) {
- kfree(full_path);
rc = -ENOMEM;
- free_xid(xid);
- return rc;
+ goto mknod_out;
if (backup_cred(cifs_sb))
@@ -742,7 +743,7 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode,
pdev->minor = cpu_to_le64(MINOR(device_number));
rc = tcon->ses->server->ops->sync_write(xid, &fid, &io_parms,
&bytes_written, iov, 1);
- } /* else if (S_ISFIFO) */
+ }
tcon->ses->server->ops->close(xid, tcon, &fid);