[PATCH 1/1] usb: gadget: f_tcm: out of bound access in usbg_drop_tpg

From: Heinrich Schuchardt
Date: Sun May 08 2016 - 16:51:05 EST


Commit dc8c46a5ae77 ("usb: gadget: f_tcm: convert to new function
interface with backward compatibility") introduced a possible out
of bounds memory access:

If tpg is not found in function usbg_drop_tpg,
tpg_instances[TPG_INSTANCES] is accessed.

Fixes: dc8c46a5ae77 ("usb: gadget: f_tcm: convert to new function interface with backward compatibility")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@xxxxxx>
---
drivers/usb/gadget/function/f_tcm.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 2ace029..9ab94b6 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1454,16 +1454,18 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)
for (i = 0; i < TPG_INSTANCES; ++i)
if (tpg_instances[i].tpg == tpg)
break;
- if (i < TPG_INSTANCES)
+ if (i < TPG_INSTANCES) {
tpg_instances[i].tpg = NULL;
- opts = container_of(tpg_instances[i].func_inst,
- struct f_tcm_opts, func_inst);
- mutex_lock(&opts->dep_lock);
- if (opts->has_dep)
- module_put(opts->dependent);
- else
- configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item);
- mutex_unlock(&opts->dep_lock);
+ opts = container_of(tpg_instances[i].func_inst,
+ struct f_tcm_opts, func_inst);
+ mutex_lock(&opts->dep_lock);
+ if (opts->has_dep)
+ module_put(opts->dependent);
+ else
+ configfs_undepend_item_unlocked(
+ &opts->func_inst.group.cg_item);
+ mutex_unlock(&opts->dep_lock);
+ }
mutex_unlock(&tpg_instances_lock);

kfree(tpg);
--
2.1.4