Commit 85db6b7a authored by Ronnie Sahlberg's avatar Ronnie Sahlberg Committed by Steve French
Browse files

cifs: make sure we do not overflow the max EA buffer size 



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: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
parent 2c6251ad

fs/cifs/smb2ops.c

+34 −1
Original line number Diff line number Diff line
@@ -1116,7 +1116,8 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon, 
	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;
@@ -1139,6 +1140,38 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon, 
							     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;

			}

		}

	}

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