4.19-stable review patch. If anyone has any objections, please let me know.
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From: Ross Lagerwall ross.lagerwall@citrix.com
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 ross.lagerwall@citrix.com Signed-off-by: Steve French stfrench@microsoft.com CC: Stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/file.c | 8 ++++---- fs/cifs/smb2file.c | 4 ++-- 2 files changed, 6 insertions(+), 6 deletions(-)
--- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -1120,10 +1120,10 @@ cifs_push_mandatory_locks(struct cifsFil
/* * 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; } @@ -1460,10 +1460,10 @@ cifs_unlock_range(struct cifsFileInfo *c
/* * 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)) / --- a/fs/cifs/smb2file.c +++ b/fs/cifs/smb2file.c @@ -122,10 +122,10 @@ smb2_unlock_range(struct cifsFileInfo *c
/* * 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);