[PATCH 3.12 51/66] target: Don't call TFO->write_pending if data_length == 0

From: Jiri Slaby
Date: Sat Dec 06 2014 - 10:18:35 EST

From: Roland Dreier <roland@xxxxxxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit 885e7b0e181c14e4d0ddd26c688bad2b84c1ada9 upstream.

If an initiator sends a zero-length command (e.g. TEST UNIT READY) but
sets the transfer direction in the transport layer to indicate a
data-out phase, we still shouldn't try to transfer data. At best it's
a NOP, and depending on the transport, we might crash on an
uninitialized sg list.

Reported-by: Craig Watson <craig.watson@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
drivers/target/target_core_transport.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index b37371ee9f95..3931b50eeefd 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2231,7 +2231,7 @@ transport_generic_new_cmd(struct se_cmd *cmd)
* and let it call back once the write buffers are ready.
- if (cmd->data_direction != DMA_TO_DEVICE) {
+ if (cmd->data_direction != DMA_TO_DEVICE || cmd->data_length == 0) {
return 0;

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