From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9931F22B5AC; Tue, 10 Feb 2026 06:08:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770703690; cv=none; b=WPjKd6t+jTmvodey7Cj5Edg3hzY+SBjc3l4DWHxgI3z+wQLJ0bfc1wyXkTR93FBTnz+xKa+ykau+XC803A6F+6m9tJnqucdkpfqMy2TL1y0HJkSlz+/nMrQ4SLAMkoRDxe8uhiYjrpF0hHu4pZEss4X+1v/d5KVdn5sOCoqIqdU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770703690; c=relaxed/simple; bh=yEB+we77jei6NeNin4hjlX2lMwU6tG4XNQB8aDO+nM0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OqBc1kIqDsJXnH5jkrM4j5SCLXAo8UkPLnMkSwdMOJsIJqocsslRDf2qsGkxVWpsFzz0JnxaLh2Gg4Tq0laDc/Z4q9Z2koVDwuTWhv3Rc/eyv5UWc899Bmwg0y0akGfeM8G1lxo0vzSgOE/dn+sdSrDzeR20w/EV5oYaqxZEoDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=te3z+m8z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="te3z+m8z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1530FC116C6; Tue, 10 Feb 2026 06:08:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770703690; bh=yEB+we77jei6NeNin4hjlX2lMwU6tG4XNQB8aDO+nM0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=te3z+m8zKLp6BpAJ9XkH5Lt6A75lAuun5KEtLtngmR0wtqOrJxTJ+vipb716i3uD2 NIx21fcMEeS8wq0BhrtOrXS+vW6S//TbUZcrz+tIUNYwrR+Vtao3w6o6OAT+p5KtVv bPeSzQSfUpKTlzHPKHZd38Svy3JgvTRKR61jb9l3GsW5LP2Hb3qLEgr4KOlwmoL/1A CQNbgpEjtgrkdAQCNY9kFUgc8ymQRcrbb7aZE2KFtd1DI9J2wq+X7lSPhyNv5DxHuo jdwtEDNUMWEddb57ZLJUf3TVwWzHJ/ZgrieTeGUPEAtNGbYeZ9aDmCz/6Sy3uaipfh lf7FHwqnADSjg== Date: Tue, 10 Feb 2026 11:38:03 +0530 From: Sumit Garg To: Amirreza Zarrabi Cc: Jens Wiklander , Arnd Bergmann , Michael Wu , linux-arm-msm@vger.kernel.org, op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] tee: optee: prevent use-after-free when the client exits before the supplicant Message-ID: References: <20260209-fix-use-after-free-v4-1-7c4c4b02368f@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260209-fix-use-after-free-v4-1-7c4c4b02368f@oss.qualcomm.com> On Mon, Feb 09, 2026 at 06:47:39PM -0800, Amirreza Zarrabi wrote: > Commit 70b0d6b0a199 ("tee: optee: Fix supplicant wait loop") made the > client wait as killable so it can be interrupted during shutdown or > after a supplicant crash. This changes the original lifetime expectations: > the client task can now terminate while the supplicant is still processing > its request. > > If the client exits first it removes the request from its queue and > kfree()s it, while the request ID remains in supp->idr. A subsequent > lookup on the supplicant path then dereferences freed memory, leading to > a use-after-free. > > Serialise access to the request with supp->mutex: > > * Hold supp->mutex in optee_supp_recv() and optee_supp_send() while > looking up and touching the request. > * Let optee_supp_thrd_req() notice that the client has terminated and > signal optee_supp_send() accordingly. > > With these changes the request cannot be freed while the supplicant still > has a reference, eliminating the race. > > Fixes: 70b0d6b0a199 ("tee: optee: Fix supplicant wait loop") > Signed-off-by: Amirreza Zarrabi > --- > Changes in v4: > - Pre-allocate request ID when allocating the request. > - Cleanup the loop in optee_supp_recv(). > - Update the return value for revoked request from -ENOENT to -EBADF. > - Link to v3: https://lore.kernel.org/r/20260128-fix-use-after-free-v3-1-b0786670d927@oss.qualcomm.com > > Changes in v3: > - Introduce processed flag instead of -1 for req->id. > - Update optee_supp_release() as reported by Michael Wu. > - Use mutex instead of guard. > - Link to v2: https://lore.kernel.org/r/20250617-fix-use-after-free-v2-1-1fbfafec5917@oss.qualcomm.com > > Changes in v2: > - Replace the static variable with a sentinel value. > - Fix the issue with returning the popped request to the supplicant. > - Link to v1: https://lore.kernel.org/r/20250605-fix-use-after-free-v1-1-a70d23bff248@oss.qualcomm.com > --- > drivers/tee/optee/supp.c | 106 ++++++++++++++++++++++++++++++++--------------- > 1 file changed, 73 insertions(+), 33 deletions(-) Looks like a reasonable fix to me but needs a reproducer where this actually fixes the mentioned problem. -Sumit > diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c > index d0f397c90242..c1ae76df7067 100644 > --- a/drivers/tee/optee/supp.c > +++ b/drivers/tee/optee/supp.c > @@ -10,7 +10,11 @@ > struct optee_supp_req { > struct list_head link; > > + int id; > + > bool in_queue; > + bool processed; > + > u32 func; > u32 ret; > size_t num_params; > @@ -19,6 +23,9 @@ struct optee_supp_req { > struct completion c; > }; > > +/* It is temporary request used for revoked pending request in supp->idr. */ > +#define INVALID_REQ_PTR ((struct optee_supp_req *)ERR_PTR(-EBADF)) > + > void optee_supp_init(struct optee_supp *supp) > { > memset(supp, 0, sizeof(*supp)); > @@ -39,21 +46,23 @@ void optee_supp_release(struct optee_supp *supp) > { > int id; > struct optee_supp_req *req; > - struct optee_supp_req *req_tmp; > > mutex_lock(&supp->mutex); > > - /* Abort all request retrieved by supplicant */ > + /* Abort all request */ > idr_for_each_entry(&supp->idr, req, id) { > idr_remove(&supp->idr, id); > - req->ret = TEEC_ERROR_COMMUNICATION; > - complete(&req->c); > - } > + /* Skip if request was already marked invalid */ > + if (IS_ERR(req)) > + continue; > > - /* Abort all queued requests */ > - list_for_each_entry_safe(req, req_tmp, &supp->reqs, link) { > - list_del(&req->link); > - req->in_queue = false; > + /* For queued requests where supplicant has not seen it */ > + if (req->in_queue) { > + list_del(&req->link); > + req->in_queue = false; > + } > + > + req->processed = true; > req->ret = TEEC_ERROR_COMMUNICATION; > complete(&req->c); > } > @@ -93,6 +102,12 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, > if (!req) > return TEEC_ERROR_OUT_OF_MEMORY; > > + req->id = idr_alloc(&supp->idr, req, 1, 0, GFP_KERNEL); > + if (req->id < 0) { > + kfree(req); > + return TEEC_ERROR_OUT_OF_MEMORY; > + } > + > init_completion(&req->c); > req->func = func; > req->num_params = num_params; > @@ -102,6 +117,7 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, > mutex_lock(&supp->mutex); > list_add_tail(&req->link, &supp->reqs); > req->in_queue = true; > + req->processed = false; > mutex_unlock(&supp->mutex); > > /* Tell an eventual waiter there's a new request */ > @@ -117,21 +133,43 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, > if (wait_for_completion_killable(&req->c)) { > mutex_lock(&supp->mutex); > if (req->in_queue) { > + /* Supplicant has not seen this request yet. */ > + idr_remove(&supp->idr, req->id); > list_del(&req->link); > req->in_queue = false; > + > + ret = TEEC_ERROR_COMMUNICATION; > + } else if (req->processed) { > + /* > + * Supplicant has processed this request. Ignore the > + * kill signal for now and submit the result. req is not > + * in supp->reqs (removed by supp_pop_entry()) nor in > + * supp->idr (removed by supp_pop_req()). > + */ > + ret = req->ret; > + } else { > + /* > + * Supplicant is in the middle of processing this > + * request. Replace req with INVALID_REQ_PTR so that > + * the ID remains busy, causing optee_supp_send() to > + * fail on the next call to supp_pop_req() with this ID. > + */ > + idr_replace(&supp->idr, INVALID_REQ_PTR, req->id); > + ret = TEEC_ERROR_COMMUNICATION; > } > + > mutex_unlock(&supp->mutex); > - req->ret = TEEC_ERROR_COMMUNICATION; > + } else { > + ret = req->ret; > } > > - ret = req->ret; > kfree(req); > > return ret; > } > > static struct optee_supp_req *supp_pop_entry(struct optee_supp *supp, > - int num_params, int *id) > + int num_params) > { > struct optee_supp_req *req; > > @@ -153,10 +191,6 @@ static struct optee_supp_req *supp_pop_entry(struct optee_supp *supp, > return ERR_PTR(-EINVAL); > } > > - *id = idr_alloc(&supp->idr, req, 1, 0, GFP_KERNEL); > - if (*id < 0) > - return ERR_PTR(-ENOMEM); > - > list_del(&req->link); > req->in_queue = false; > > @@ -214,7 +248,6 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, > struct optee *optee = tee_get_drvdata(teedev); > struct optee_supp *supp = &optee->supp; > struct optee_supp_req *req = NULL; > - int id; > size_t num_meta; > int rc; > > @@ -224,15 +257,11 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, > > while (true) { > mutex_lock(&supp->mutex); > - req = supp_pop_entry(supp, *num_params - num_meta, &id); > + req = supp_pop_entry(supp, *num_params - num_meta); > + if (req) > + break; /* Keep mutex held. */ > mutex_unlock(&supp->mutex); > > - if (req) { > - if (IS_ERR(req)) > - return PTR_ERR(req); > - break; > - } > - > /* > * If we didn't get a request we'll block in > * wait_for_completion() to avoid needless spinning. > @@ -245,6 +274,13 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, > return -ERESTARTSYS; > } > > + /* supp->mutex held and req != NULL. */ > + > + if (IS_ERR(req)) { > + mutex_unlock(&supp->mutex); > + return PTR_ERR(req); > + } > + > if (num_meta) { > /* > * tee-supplicant support meta parameters -> requsts can be > @@ -252,13 +288,11 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, > */ > param->attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT | > TEE_IOCTL_PARAM_ATTR_META; > - param->u.value.a = id; > + param->u.value.a = req->id; > param->u.value.b = 0; > param->u.value.c = 0; > } else { > - mutex_lock(&supp->mutex); > - supp->req_id = id; > - mutex_unlock(&supp->mutex); > + supp->req_id = req->id; > } > > *func = req->func; > @@ -266,6 +300,7 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, > memcpy(param + num_meta, req->param, > sizeof(struct tee_param) * req->num_params); > > + mutex_unlock(&supp->mutex); > return 0; > } > > @@ -297,12 +332,17 @@ static struct optee_supp_req *supp_pop_req(struct optee_supp *supp, > if (!req) > return ERR_PTR(-ENOENT); > > + /* optee_supp_thrd_req() already returned to optee. */ > + if (IS_ERR(req)) > + goto failed_req; > + > if ((num_params - nm) != req->num_params) > return ERR_PTR(-EINVAL); > > + *num_meta = nm; > +failed_req: > idr_remove(&supp->idr, id); > supp->req_id = -1; > - *num_meta = nm; > > return req; > } > @@ -328,10 +368,9 @@ int optee_supp_send(struct tee_context *ctx, u32 ret, u32 num_params, > > mutex_lock(&supp->mutex); > req = supp_pop_req(supp, num_params, param, &num_meta); > - mutex_unlock(&supp->mutex); > - > if (IS_ERR(req)) { > - /* Something is wrong, let supplicant restart. */ > + mutex_unlock(&supp->mutex); > + /* Something is wrong, let supplicant handel it. */ > return PTR_ERR(req); > } > > @@ -355,9 +394,10 @@ int optee_supp_send(struct tee_context *ctx, u32 ret, u32 num_params, > } > } > req->ret = ret; > - > + req->processed = true; > /* Let the requesting thread continue */ > complete(&req->c); > + mutex_unlock(&supp->mutex); > > return 0; > } > > --- > base-commit: 3f24e4edcd1b8981c6b448ea2680726dedd87279 > change-id: 20250604-fix-use-after-free-8ff1b5d5d774 > > Best regards, > -- > Amirreza Zarrabi >