I am hitting this bug when the target is low in memory that fails the
alloc_page() for the newly submitted command. This is a sort of off-by-one
bug causing NULL pointer dereference in __free_page() since 'i' here is
really the counter of total pages that have been successfully allocated here.

Signed-off-by: Yi Zou <yi....@intel.com>
Cc: Andy Grover <agro...@redhat.com>
Cc: Nicholas Bellinger <n...@linux-iscsi.org>
Cc: Open-FCoE.org <devel@open-fcoe.org>
---

 drivers/target/target_core_transport.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_transport.c 
b/drivers/target/target_core_transport.c
index 0eaae23..a7589cc 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2294,9 +2294,9 @@ transport_generic_get_mem(struct se_cmd *cmd)
        return 0;
 
 out:
-       while (i >= 0) {
-               __free_page(sg_page(&cmd->t_data_sg[i]));
+       while (i > 0) {
                i--;
+               __free_page(sg_page(&cmd->t_data_sg[i]));
        }
        kfree(cmd->t_data_sg);
        cmd->t_data_sg = NULL;

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