Re: [PATCH] nvmet-auth: fix out-of-bounds write in nvmet_auth_challenge()

[Hannes Reinecke]

On 9/12/26 7:10 PM, Weiming Shi wrote:
> nvmet_auth_challenge() receives its output buffer as a void pointer.
> sizeof(*d) therefore evaluates to one with GCC and undercounts the fixed
> challenge header by 15 bytes.  A short AUTH_RECEIVE buffer can pass the
> check before the challenge is copied past the end of its allocation.
>
> Use the typed challenge pointer when calculating the response size.
>
>    BUG: KASAN: slab-out-of-bounds in nvmet_execute_auth_receive (drivers/nvme/target/fabrics-cmd-auth.c:442 drivers/nvme/target/fabrics-cmd-auth.c:569)
>    Write of size 32 by task kworker/1:1H/64
>    Workqueue: nvmet_tcp_wq nvmet_tcp_io_work
>    Call Trace:
>    nvmet_execute_auth_receive (drivers/nvme/target/fabrics-cmd-auth.c:442 drivers/nvme/target/fabrics-cmd-auth.c:569)
>    nvmet_tcp_try_recv_pdu (drivers/nvme/target/tcp.c:1119 drivers/nvme/target/tcp.c:1243)
>    nvmet_tcp_io_work (drivers/nvme/target/tcp.c:1350 drivers/nvme/target/tcp.c:1382 drivers/nvme/target/tcp.c:1445)
>    process_one_work (kernel/workqueue.c:3322)
>    worker_thread (kernel/workqueue.c:3405 kernel/workqueue.c:3486)
>    kthread (kernel/kthread.c:436)
>    ret_from_fork (arch/x86/kernel/process.c:158)
>    ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
>    The buggy address is located 16 bytes inside of
>     allocated 33-byte region [ffff888000554e80, ffff888000554ea1)
>    Kernel panic - not syncing: KASAN: panic_on_warn set ...
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: db1312dd9548 ("nvmet: implement basic In-Band Authentication")
> Reported-by: co+77553a7fc66ac133@xxxxxxx
> Closes: https://lore.kernel.org/all/Ah6QavQXwvshtqyUcYD1P1R7XE0ND9fB7lbV@xxxxxxx/
> Assisted-by: Codex:gpt-5.6
> Signed-off-by: Weiming Shi <bestswngs@xxxxxxxxx>
> ---
>   drivers/nvme/target/fabrics-cmd-auth.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
> index 92f8a76f10..dccdb55a36 100644
> --- a/drivers/nvme/target/fabrics-cmd-auth.c
> +++ b/drivers/nvme/target/fabrics-cmd-auth.c
> @@ -427,7 +427,7 @@ static int nvmet_auth_challenge(struct nvmet_req *req, void *d, int al)
>   	struct nvmet_ctrl *ctrl = req->sq->ctrl;
>   	int ret = 0;
>   	int hash_len = nvme_auth_hmac_hash_len(ctrl->shash_id);
> -	int data_size = sizeof(*d) + hash_len;
> +	int data_size = sizeof(*data) + hash_len;
>   
>   	if (ctrl->dh_tfm)
>   		data_size += ctrl->dh_keysize;

Reviewed-by: Hannes Reinecke <hare@xxxxxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@xxxxxxx                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich