OP-TEE February 2026

op-tee@lists.trustedfirmware.org

15 participants
12 discussions

[PATCH v3] tee: optee: prevent use-after-free when the client exits before the supplicant

by Amirreza Zarrabi

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 <amirreza.zarrabi(a)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… 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… --- drivers/tee/optee/supp.c | 122 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 86 insertions(+), 36 deletions(-) diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c index d0f397c90242..0ec66008df19 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 invalid pending request in supp->idr. */ +#define INVALID_REQ_PTR ((struct optee_supp_req *)ERR_PTR(-ENOENT)) + void optee_supp_init(struct optee_supp *supp) { memset(supp, 0, sizeof(*supp)); @@ -46,6 +53,10 @@ void optee_supp_release(struct optee_supp *supp) /* Abort all request retrieved by supplicant */ idr_for_each_entry(&supp->idr, req, id) { idr_remove(&supp->idr, id); + /* Skip if request was already marked invalid */ + if (IS_ERR(req)) + continue; + req->ret = TEEC_ERROR_COMMUNICATION; complete(&req->c); } @@ -102,6 +113,7 @@ 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 +129,40 @@ 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. */ 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. + */ + 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; @@ -153,8 +184,8 @@ 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) + req->id = idr_alloc(&supp->idr, req, 1, 0, GFP_KERNEL); + if (req->id < 0) return ERR_PTR(-ENOMEM); list_del(&req->link); @@ -214,7 +245,6 @@ 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 +254,48 @@ 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); - mutex_unlock(&supp->mutex); - if (req) { - if (IS_ERR(req)) - return PTR_ERR(req); - break; + req = supp_pop_entry(supp, *num_params - num_meta); + if (!req) { + mutex_unlock(&supp->mutex); + goto wait_for_request; + } + + if (IS_ERR(req)) { + rc = PTR_ERR(req); + mutex_unlock(&supp->mutex); + + return rc; } + /* + * Process the request while holding the lock, so that + * optee_supp_thrd_req() doesn't pull the request from under us. + */ + + if (num_meta) { + /* + * tee-supplicant support meta parameters -> + * requests can be processed asynchronously. + */ + param->attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT | + TEE_IOCTL_PARAM_ATTR_META; + param->u.value.a = req->id; + param->u.value.b = 0; + param->u.value.c = 0; + } else { + supp->req_id = req->id; + } + + *func = req->func; + *num_params = req->num_params + num_meta; + memcpy(param + num_meta, req->param, + sizeof(struct tee_param) * req->num_params); + + mutex_unlock(&supp->mutex); + return 0; + +wait_for_request: /* * If we didn't get a request we'll block in * wait_for_completion() to avoid needless spinning. @@ -243,29 +306,10 @@ int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params, */ if (wait_for_completion_interruptible(&supp->reqs_c)) return -ERESTARTSYS; - } - if (num_meta) { - /* - * tee-supplicant support meta parameters -> requsts can be - * processed asynchronously. - */ - param->attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT | - TEE_IOCTL_PARAM_ATTR_META; - param->u.value.a = id; - param->u.value.b = 0; - param->u.value.c = 0; - } else { - mutex_lock(&supp->mutex); - supp->req_id = id; - mutex_unlock(&supp->mutex); + /* Check for the next request in the queue. */ } - *func = req->func; - *num_params = req->num_params + num_meta; - memcpy(param + num_meta, req->param, - sizeof(struct tee_param) * req->num_params); - return 0; } @@ -297,12 +341,18 @@ 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; } @@ -328,9 +378,8 @@ 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)) { + mutex_unlock(&supp->mutex); /* Something is wrong, let supplicant restart. */ return PTR_ERR(req); } @@ -355,9 +404,10 @@ 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 <amirreza.zarrabi(a)oss.qualcomm.com>

2 weeks, 3 days

OP-TEE: memory corruption in scmi_pin_control_list_associations_handler()

by Dan Carpenter

When we do SCMI on OP-TEE, the in buffer and out buffer are the same buffer. I added some debug code to confirm this: diff --git a/module/msg_smt/src/mod_msg_smt.c b/module/msg_smt/src/mod_msg_smt.c index 853fe66b8d27..1e92dcd49c29 100644 --- a/module/msg_smt/src/mod_msg_smt.c +++ b/module/msg_smt/src/mod_msg_smt.c @@ -175,6 +175,11 @@ static int smt_write_payload(fwk_id_t channel_id, if (!channel_ctx->locked) return FWK_E_ACCESS; + FWK_LOG_ERR("OUT=%p IN=%p %s", + channel_ctx->out->payload, + channel_ctx->in->payload, + (channel_ctx->out->payload == channel_ctx->in->payload) ? "equal" : "different"); + memcpy(((uint8_t*)channel_ctx->out->payload) + offset, payload, size); return FWK_SUCCESS; And it's true: [ 0.000000] OUT=0x9c401004 IN=0x9c401004 equal This normally isn't a problem because we read a few inputs at the start of the function and then write out the result to the output at the end. But in the scmi_pin_control_list_associations_handler() it does a loop where each iteration reads from parameters->index which is input and writes to the output with scmi_pin_control_ctx.scmi_api->write_payload() and that corrupts the input data. Copying the input buffer to a the stack the issue for me, but I feel like it is a hack. It would be better to use separate buffers for input and output. I think this comes from: https://github.com/OP-TEE/optee_os/blob/master/core/kernel/pseudo_ta.c#L93 I added a print statement to there as well: diff --git a/core/kernel/pseudo_ta.c b/core/kernel/pseudo_ta.c index 587faa41a770..426870fb934c 100644 --- a/core/kernel/pseudo_ta.c +++ b/core/kernel/pseudo_ta.c @@ -90,6 +90,7 @@ static TEE_Result copy_in_param(struct ts_session *s __maybe_unused, va = NULL; } + EMSG("n=%lu va=%p", n, va); tee_param[n].memref.buffer = va; tee_param[n].memref.size = mem->size; break; E/TC:? 0 copy_in_param:93 n=1 va=0x9c401000 E/TC:? 0 copy_in_param:93 n=2 va=0x9c401000 Here is the patch to save "parameters" to a different buffer. --- .../scmi_pin_control/src/mod_scmi_pin_control.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/module/scmi_pin_control/src/mod_scmi_pin_control.c b/module/scmi_pin_control/src/mod_scmi_pin_control.c index a0b90dd2b73f..54e613b70f69 100644 --- a/module/scmi_pin_control/src/mod_scmi_pin_control.c +++ b/module/scmi_pin_control/src/mod_scmi_pin_control.c @@ -344,7 +344,7 @@ static int scmi_pin_control_list_associations_handler( fwk_id_t service_id, const uint32_t *payload) { - const struct scmi_pin_control_list_associations_a2p *parameters; + const struct scmi_pin_control_list_associations_a2p parameters; uint32_t payload_size; uint16_t identifiers_count; uint16_t total_number_of_associations; @@ -362,8 +362,9 @@ static int scmi_pin_control_list_associations_handler( payload_size = (uint32_t)sizeof(return_values); parameters = (const struct scmi_pin_control_list_associations_a2p *)payload; + memcpy(&parameters, payload, sizeof(parameters)); - status = map_identifier(parameters->identifier, &mapped_identifier); + status = map_identifier(parameters.identifier, &mapped_identifier); if (status != FWK_SUCCESS) { return_values.status = SCMI_NOT_FOUND; @@ -371,7 +372,7 @@ static int scmi_pin_control_list_associations_handler( } status = scmi_pin_control_ctx.pinctrl_api->get_total_number_of_associations( - mapped_identifier, parameters->flags, &total_number_of_associations); + mapped_identifier, parameters.flags, &total_number_of_associations); if (status != FWK_SUCCESS) { return_values.status = SCMI_NOT_FOUND; goto exit; @@ -388,11 +389,11 @@ static int scmi_pin_control_list_associations_handler( identifiers_count = (uint16_t)FWK_MIN( buffer_allowed_identifiers, - (uint16_t)(total_number_of_associations - parameters->index)); + (uint16_t)(total_number_of_associations - parameters.index)); return_values.flags = identifiers_count; return_values.flags |= SHIFT_LEFT_BY_POS( - (total_number_of_associations - parameters->index - identifiers_count), + (total_number_of_associations - parameters.index - identifiers_count), NUM_OF_REMAINING_ELEMENTS_POS); for (identifier_index = 0; identifier_index < identifiers_count; @@ -401,8 +402,8 @@ static int scmi_pin_control_list_associations_handler( status = scmi_pin_control_ctx.pinctrl_api->get_list_associations( mapped_identifier, - parameters->flags, - (parameters->index + identifier_index), + parameters.flags, + (parameters.index + identifier_index), &object_id); if (status != FWK_SUCCESS) { return_values.status = SCMI_NOT_FOUND; -- 2.51.0

2 weeks, 3 days

2026

2025

2024

2023

2022

2021

2020

OP-TEE February 2026