[Devel] [PATCH RHEL7 COMMIT] ms/target: bounds check XCOPY total descriptor list length

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.21.1.vz7.46.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.21.1.vz7.46.3
------>
commit 974c80aae4c05690946432b0a6133d87cb55eb73
Author: David Disseldorp <ddiss at suse.de>
Date:   Tue Apr 3 16:11:34 2018 +0300

    ms/target: bounds check XCOPY total descriptor list length
    
    ML: 7d38706669ce00603b187f667a4eb67c94eac098
    
    spc4r37 6.4.3.5 states:
      If the combined length of the CSCD descriptors and segment descriptors
      exceeds the allowed value, then the copy manager shall terminate the
      command with CHECK CONDITION status, with the sense key set to ILLEGAL
      REQUEST, and the additional sense code set to PARAMETER LIST LENGTH
      ERROR.
    
    This functionality can be tested using the libiscsi
    ExtendedCopy.DescrLimits test.
    
    Signed-off-by: David Disseldorp <ddiss at suse.de>
    Reviewed-by: Christoph Hellwig <hch at lst.de>
    Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
    Signed-off-by: Andrei Vagin <avagin at openvz.org>
---
 drivers/target/target_core_xcopy.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index d8d53c4f83b8..f2ea6cc02c26 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -940,6 +940,12 @@ sense_reason_t target_do_xcopy(struct se_cmd *se_cmd)
 	 */
 	tdll = get_unaligned_be16(&p[2]);
 	sdll = get_unaligned_be32(&p[8]);
+	if (tdll + sdll > RCR_OP_MAX_DESC_LIST_LEN) {
+		pr_err("XCOPY descriptor list length %u exceeds maximum %u\n",
+		       tdll + sdll, RCR_OP_MAX_DESC_LIST_LEN);
+		ret = TCM_PARAMETER_LIST_LENGTH_ERROR;
+		goto out;
+	}
 
 	inline_dl = get_unaligned_be32(&p[12]);
 	if (inline_dl != 0) {