From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Thu, 13 Feb 2020 12:14:47 +1000
Subject: [PATCH] cifs: make sure we do not overflow the max EA buffer size
Git-commit: 85db6b7ae65f33be4bb44f1c28261a3faa126437
References: bsc#1144333
Patch-mainline: v5.6-rc2
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>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
fs/cifs/smb2ops.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index aef33630e315..e47190cae163 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -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;
+ }
}
}
--
2.25.1