From: Ronnie Sahlberg lsahlber@redhat.com
commit 85db6b7ae65f33be4bb44f1c28261a3faa126437 upstream.
RHBZ: 1752437
Before we add a new EA we should check that this will not overflow the maximum buffer we have available to read the EAs back. Otherwise we can get into a situation where the EAs are so big that we can not read them back to the client and thus we can not list EAs anymore or delete them.
Signed-off-by: Ronnie Sahlberg lsahlber@redhat.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/smb2ops.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-)
--- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1115,7 +1115,8 @@ smb2_set_ea(const unsigned int xid, stru void *data[1]; struct smb2_file_full_ea_info *ea = NULL; struct kvec close_iov[1]; - int rc; + struct smb2_query_info_rsp *rsp; + int rc, used_len = 0;
if (smb3_encryption_required(tcon)) flags |= CIFS_TRANSFORM_REQ; @@ -1138,6 +1139,38 @@ smb2_set_ea(const unsigned int xid, stru cifs_sb); if (rc == -ENODATA) goto sea_exit; + } else { + /* If we are adding a attribute we should first check + * if there will be enough space available to store + * the new EA. If not we should not add it since we + * would not be able to even read the EAs back. + */ + rc = smb2_query_info_compound(xid, tcon, utf16_path, + FILE_READ_EA, + FILE_FULL_EA_INFORMATION, + SMB2_O_INFO_FILE, + CIFSMaxBufSize - + MAX_SMB2_CREATE_RESPONSE_SIZE - + MAX_SMB2_CLOSE_RESPONSE_SIZE, + &rsp_iov[1], &resp_buftype[1], cifs_sb); + if (rc == 0) { + rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base; + used_len = le32_to_cpu(rsp->OutputBufferLength); + } + free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base); + resp_buftype[1] = CIFS_NO_BUFFER; + memset(&rsp_iov[1], 0, sizeof(rsp_iov[1])); + rc = 0; + + /* Use a fudge factor of 256 bytes in case we collide + * with a different set_EAs command. + */ + if(CIFSMaxBufSize - MAX_SMB2_CREATE_RESPONSE_SIZE - + MAX_SMB2_CLOSE_RESPONSE_SIZE - 256 < + used_len + ea_name_len + ea_value_len + 1) { + rc = -ENOSPC; + goto sea_exit; + } } }