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authorNicholas Bellinger <nab@linux-iscsi.org>2012-10-02 14:00:33 -0700
committerNicholas Bellinger <nab@linux-iscsi.org>2012-10-02 14:16:19 -0700
commit944981c7e106af2aa004847e9177497856630980 (patch)
treecc3f3e84f26a13c18adb7b84055147ed9ea45b88 /drivers/target
parent8f9f44f8957b262de717a48269a5ceca36c2b504 (diff)
downloadlinux-944981c7e106af2aa004847e9177497856630980.tar.gz
target: Add control CDB READ payload zero work-around
This patch carries forward a work-around from tcm_loop to target
core code to explicitly clear control CDB READ paylods in order to
avoid bugs in scsi-generic user-space code for INQUIRY that do not
explicitly zero CDB payload memory.

(v2: Drop TARGET_SCF_MAP_CLEAR_MEM, and perform the explicit zero
     of READ memory for all target_submit_cmd_map_sgls users)

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target')
-rw-r--r--drivers/target/target_core_transport.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index d96d9aa3a496..c33baff86aa6 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1539,6 +1539,27 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
 	if (sgl_count != 0) {
 		BUG_ON(!sgl);
 
+		/*
+		 * A work-around for tcm_loop as some userspace code via
+		 * scsi-generic do not memset their associated read buffers,
+		 * so go ahead and do that here for type non-data CDBs.  Also
+		 * note that this is currently guaranteed to be a single SGL
+		 * for this case by target core in target_setup_cmd_from_cdb()
+		 * -> transport_generic_cmd_sequencer().
+		 */
+		if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
+		     se_cmd->data_direction == DMA_FROM_DEVICE) {
+			unsigned char *buf = NULL;
+
+			if (sgl)
+				buf = kmap(sg_page(sgl)) + sgl->offset;
+
+			if (buf) {
+				memset(buf, 0, sgl->length);
+				kunmap(sg_page(sgl));
+			}
+		}
+
 		rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
 				sgl_bidi, sgl_bidi_count);
 		if (rc != 0) {