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SubjectRe: [patch -target tree] usb: gadget: f_tcm: use after free
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Hi Nicholas,

W dniu 10.03.2016 o 06:19, Nicholas A. Bellinger pisze:
> Hi Andrzej,
>
> On Wed, 2016-03-09 at 13:53 +0100, Andrzej Pietrasiewicz wrote:
>> Hi Nicholas,
>>

<snip>

>
> Applying the following patch to re-add the missing assingment
> as a proper alloc_session callback.
>
> diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
> index e352a31..348140c 100644
> --- a/drivers/usb/gadget/function/f_tcm.c
> +++ b/drivers/usb/gadget/function/f_tcm.c
> @@ -1570,6 +1570,16 @@ out:
> return ret;
> }
>
> +static int usbg_alloc_sess_cb(struct se_portal_group *se_tpg,
> + struct se_session *se_sess, void *p)
> +{
> + struct usbg_tpg *tpg = container_of(se_tpg,
> + struct usbg_tpg, se_tpg);
> +
> + tpg->tpg_nexus = p;
> + return 0;
> +}
> +
> static int tcm_usbg_make_nexus(struct usbg_tpg *tpg, char *name)
> {
> struct tcm_usbg_nexus *tv_nexus;
> @@ -1591,7 +1601,7 @@ static int tcm_usbg_make_nexus(struct usbg_tpg *tpg, char *name)
> tv_nexus->tvn_se_sess = target_alloc_session(&tpg->se_tpg, 128,
> sizeof(struct usbg_cmd),
> TARGET_PROT_NORMAL, name,
> - tv_nexus, NULL);
> + tv_nexus, usbg_alloc_sess_cb);
> if (IS_ERR(tv_nexus->tvn_se_sess)) {
> #define MAKE_NEXUS_MSG "core_tpg_check_initiator_node_acl() failed for %s\n"
> pr_debug(MAKE_NEXUS_MSG, name);
>

<snip>

>
> Mmmm, usbg_get_cmd() was missing an explicit memset() after tag lookup.
>
> How about the following..?
>
> diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
> index e352a31..d4e8a91 100644
> --- a/drivers/usb/gadget/function/f_tcm.c
> +++ b/drivers/usb/gadget/function/f_tcm.c
> @@ -1078,6 +1078,7 @@ static struct usbg_cmd *usbg_get_cmd(struct f_uas *fu,
> return ERR_PTR(-ENOMEM);
>
> cmd = &((struct usbg_cmd *)se_sess->sess_cmd_map)[tag];
> + memset(cmd, 0, sizeof(*cmd));
> cmd->se_cmd.map_tag = tag;
> cmd->se_cmd.tag = cmd->tag = scsi_tag;
> cmd->fu = fu;
>
>
>

I tested it. Works for me.

AP

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