target_core_rd: break out unterminated loop during copy

The loop in rd_execute_rw() will never terminate if the
sg element has a zero size. Or it'll spill over into
outer space if the sg element is larger than the available
space.
So we need to add some safety catches here.

Cc: Nic Bellinger <nab@risingtidesystems.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index b0fff52c990e..e0b3c379aa14 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -316,7 +316,19 @@ rd_execute_rw(struct se_cmd *cmd)
                 void *rd_addr;
 
                 sg_miter_next(&m);
+                if (!(u32)m.length) {
+                        pr_debug("RD[%u]: invalid sgl %p len %zu\n",
+                                 dev->rd_dev_id, m.addr, m.length);
+                        sg_miter_stop(&m);
+                        return TCM_INCORRECT_AMOUNT_OF_DATA;
+                }
                 len = min((u32)m.length, src_len);
+                if (len > rd_size) {
+                        pr_debug("RD[%u]: size underrun page %d offset %d "
+                                 "size %d\n", dev->rd_dev_id,
+                                 rd_page, rd_offset, rd_size);
+                        len = rd_size;
+                }
                 m.consumed = len;
 
                 rd_addr = sg_virt(rd_sg) + rd_offset;