From 570287c261aee05bf4c1f482ecfe27e8cfe99068 Mon Sep 17 00:00:00 2001 From: Ross Lagerwall Date: Tue, 8 Jan 2019 18:30:57 +0000 Subject: [PATCH] cifs: Fix potential OOB access of lock element array commit b9a74cde94957d82003fb9f7ab4777938ca851cd upstream. If maxBuf is small but non-zero, it could result in a zero sized lock element array which we would then try and access OOB. Signed-off-by: Ross Lagerwall Signed-off-by: Steve French Signed-off-by: Ben Hutchings --- fs/cifs/file.c | 8 ++++---- fs/cifs/smb2file.c | 4 ++-- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 716c55ceee24..50c5e3955786 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -1066,10 +1066,10 @@ cifs_push_mandatory_locks(struct cifsFileInfo *cfile) /* * Accessing maxBuf is racy with cifs_reconnect - need to store value - * and check it for zero before using. + * and check it before using. */ max_buf = tcon->ses->server->maxBuf; - if (!max_buf) { + if (max_buf < (sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE))) { free_xid(xid); return -EINVAL; } @@ -1403,10 +1403,10 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, /* * Accessing maxBuf is racy with cifs_reconnect - need to store value - * and check it for zero before using. + * and check it before using. */ max_buf = tcon->ses->server->maxBuf; - if (!max_buf) + if (max_buf < (sizeof(struct smb_hdr) + sizeof(LOCKING_ANDX_RANGE))) return -EINVAL; max_num = (max_buf - sizeof(struct smb_hdr)) / diff --git a/fs/cifs/smb2file.c b/fs/cifs/smb2file.c index cf560ca00d97..179a50218995 100644 --- a/fs/cifs/smb2file.c +++ b/fs/cifs/smb2file.c @@ -101,10 +101,10 @@ smb2_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock, /* * Accessing maxBuf is racy with cifs_reconnect - need to store value - * and check it for zero before using. + * and check it before using. */ max_buf = tcon->ses->server->maxBuf; - if (!max_buf) + if (max_buf < sizeof(struct smb2_lock_element)) return -EINVAL; max_num = max_buf / sizeof(struct smb2_lock_element);