[PATCH 0/2] misc: fastrpc: fixes for 7.3

[PATCH 0/2] misc: fastrpc: fixes for 7.3

[Srinivas Kandagatla]

From: Srinivas Kandagatla <srini@kernel.org>

Hi Greg,

Here are few fastrpc fixes for 7.3, Could you please queue
these for 7.3.

Patches include
	- fix double-free in fastrpc_map_attach() error path
	- allocate entire Audio PD reserved memory in probe to avoid
	  userspace-controlled alloc/free and unbounded heap growth

Thanks,
Srini

Jianping Li (1):
  misc: fastrpc: Allocate entire reserved memory for Audio PD in probe

Yifei Gao (1):
  misc: fastrpc: fix double-free in fastrpc_map_attach() error path

 drivers/misc/fastrpc.c | 192 ++++++++++++++++++++++-------------------
 1 file changed, 103 insertions(+), 89 deletions(-)

-- 
2.53.0

[PATCH 1/2] misc: fastrpc: fix double-free in fastrpc_map_attach() error path

[Srinivas Kandagatla]

From: Yifei Gao <gyf161023@gmail.com>

map->table is assigned right after dma_buf_map_attachment_unlocked()
succeeds. The two failure checks that follow, the len > map->size test
and, where subsystem VMIDs are configured, a failed qcom_scm_assign_mem(),
jump to map_err with map->table already set.

map_err manually calls dma_buf_detach() and dma_buf_put() and then falls
through to fastrpc_map_put(). Since that change the error path tail is
fastrpc_map_put() -> fastrpc_free_map(), and fastrpc_free_map() already
unmaps, detaches and puts the dma-buf whenever map->table is set.
The two operations therefore run twice: the second dma_buf_put() drops an
extra reference on map->buf, and dma_buf_unmap_attachment_unlocked()
dereferences the map->attach already freed by the manual dma_buf_detach().
kref_init() sets the refcount to 1 with no intervening get, so the final
fastrpc_map_put() frees the map synchronously and the redundant cleanup is
deterministic.

The len > map->size branch is reachable by an unprivileged process via
FASTRPC_IOCTL_MEM_MAP with an fd whose dma-buf is smaller than the
requested length, before any DSP invocation.

Route both map->table-is-set failure branches to get_err instead of
map_err, so fastrpc_free_map() is the single owner of the
unmap/detach/put sequence. map_err is retained for the
dma_buf_map_attachment_unlocked() failure, which is reached with
map->table still NULL and an attachment that fastrpc_free_map() will not
clean up, so its dma_buf_detach()/dma_buf_put() must still run manually.

Fixes: 334f1a1cbe03 ("misc: fastrpc: Use fastrpc_map_put in fastrpc_map_create on fail")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Yifei Gao <gyf161023@gmail.com>
Reviewed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
---
 drivers/misc/fastrpc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 90fd669636ec..4a18081845d9 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -927,7 +927,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
 		dev_dbg(sess->dev, "Bad size passed len 0x%llx map size 0x%llx\n",
 				len, map->size);
 		err = -EINVAL;
-		goto map_err;
+		goto get_err;
 	}
 	map->va = sg_virt(map->table->sgl);
 	map->len = len;
@@ -950,7 +950,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
 			dev_err(sess->dev,
 				"Failed to assign memory with dma_addr %pad size 0x%llx err %d\n",
 				&map->dma_addr, map->len, err);
-			goto map_err;
+			goto get_err;
 		}
 	}
 	spin_lock(&fl->lock);
-- 
2.53.0

[PATCH 2/2] misc: fastrpc: Allocate entire reserved memory for Audio PD in probe

[Srinivas Kandagatla]

From: Jianping Li <jianping.li@oss.qualcomm.com>

Allocating and freeing Audio PD memory from userspace is unsafe because
the kernel cannot reliably determine when the DSP has finished using the
memory. Userspace may free buffers while they are still in use by the DSP,
and remote free requests cannot be safely trusted.

Additionally, the current implementation allows userspace to repeatedly
grow the Audio PD heap, but does not support shrinking it. This can lead
to unbounded memory usage over time, effectively causing a memory leak.

Fix this by allocating the entire Audio PD reserved-memory region during
rpmsg probe and tying its lifetime to the rpmsg channel. This removes
userspace-controlled alloc/free and ensures that memory is reclaimed only
when the DSP process is torn down.

The reserved-memory region is now mandatory for the Audio PD domain.
Rather than failing rpmsg probe when it is missing, validate it in
fastrpc_init_create_static_process() and reject only the static-process
creation. This keeps the fastrpc device probing for all other domains
even on a misconfigured device tree.

Fixes: 0871561055e66 ("misc: fastrpc: Add support for audiopd")
Cc: stable@kernel.org
Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
Reviewed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Link: https://lore.kernel.org/all/20260814101955.234238-1-jianping.li@oss.qualcomm.com/
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
---
 drivers/misc/fastrpc.c | 188 ++++++++++++++++++++++-------------------
 1 file changed, 101 insertions(+), 87 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4a18081845d9..9310ef1cb4a6 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -70,8 +70,6 @@
 #define ADSP_MMAP_HEAP_ADDR  4
 /* MAP static DMA buffer on DSP User PD */
 #define ADSP_MMAP_DMA_BUFFER  6
-/* Add memory to static PD pool protection thru hypervisor */
-#define ADSP_MMAP_REMOTE_HEAP_ADDR  8
 /* Add memory to userPD pool, for user heap */
 #define ADSP_MMAP_ADD_PAGES 0x1000
 /* Add memory to userPD pool, for LLC heap */
@@ -314,10 +312,14 @@ struct fastrpc_channel_ctx {
 	struct kref refcount;
 	/* Flag if dsp attributes are cached */
 	bool valid_attributes;
+	/* Flag if audio PD init mem was allocated */
+	bool audio_init_mem;
+	/* Audio PD reserved remote heap region */
+	phys_addr_t remote_heap_addr;
+	u64 remote_heap_size;
 	u32 dsp_attributes[FASTRPC_MAX_DSP_ATTRIBUTES];
 	struct fastrpc_device *secure_fdevice;
 	struct fastrpc_device *fdevice;
-	struct fastrpc_buf *remote_heap;
 	struct list_head invoke_interrupted_mmaps;
 	bool secure;
 	bool unsigned_support;
@@ -1454,15 +1456,24 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 	struct fastrpc_init_create_static init;
 	struct fastrpc_invoke_args *args;
 	struct fastrpc_phy_page pages[1];
+	struct fastrpc_channel_ctx *cctx = fl->cctx;
 	char *name;
 	int err;
-	bool scm_done = false;
 	struct {
 		int client_id;
 		u32 namelen;
 		u32 pageslen;
 	} inbuf;
 	u32 sc;
+	unsigned long flags;
+	bool sent_heap = false;
+
+	if (!cctx->remote_heap_addr || !cctx->remote_heap_size) {
+		err = -ENOMEM;
+		dev_err(fl->sctx->dev,
+			"remote heap memory region is not added\n");
+		return err;
+	}
 
 	args = kzalloc_objs(*args, FASTRPC_CREATE_STATIC_PROCESS_NARGS);
 	if (!args)
@@ -1486,31 +1497,6 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 	inbuf.client_id = fl->client_id;
 	inbuf.namelen = init.namelen;
 	inbuf.pageslen = 0;
-	if (!fl->cctx->remote_heap) {
-		err = fastrpc_remote_heap_alloc(fl, fl->sctx->dev, init.memlen,
-						&fl->cctx->remote_heap);
-		if (err)
-			goto err_name;
-
-		/* Map if we have any heap VMIDs associated with this ADSP Static Process. */
-		if (fl->cctx->vmcount) {
-			u64 src_perms = BIT(QCOM_SCM_VMID_HLOS);
-
-			err = qcom_scm_assign_mem(fl->cctx->remote_heap->dma_addr,
-							(u64)fl->cctx->remote_heap->size,
-							&src_perms,
-							fl->cctx->vmperms, fl->cctx->vmcount);
-			if (err) {
-				dev_err(fl->sctx->dev,
-					"Failed to assign memory with dma_addr %pad size 0x%llx err %d\n",
-					&fl->cctx->remote_heap->dma_addr,
-					fl->cctx->remote_heap->size, err);
-				goto err_map;
-			}
-			scm_done = true;
-			inbuf.pageslen = 1;
-		}
-	}
 
 	fl->pd = USER_PD;
 
@@ -1522,8 +1508,25 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 	args[1].length = inbuf.namelen;
 	args[1].fd = -1;
 
-	pages[0].addr = fl->cctx->remote_heap->dma_addr;
-	pages[0].size = fl->cctx->remote_heap->size;
+	/*
+	 * Audio PD is a static PD and retains the remote heap
+	 * information across daemon restarts. Therefore only
+	 * the first attach should provide heap information to
+	 * DSP. Subsequent attaches reuse the previously
+	 * initialized memory pool.
+	 */
+	spin_lock_irqsave(&cctx->lock, flags);
+	if (!cctx->audio_init_mem) {
+		pages[0].addr = cctx->remote_heap_addr;
+		pages[0].size = cctx->remote_heap_size;
+		cctx->audio_init_mem = true;
+		inbuf.pageslen = 1;
+		sent_heap = true;
+	} else {
+		pages[0].addr = 0;
+		pages[0].size = 0;
+	}
+	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	args[2].ptr = (u64)(uintptr_t) pages;
 	args[2].length = sizeof(*pages);
@@ -1541,27 +1544,11 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 
 	return 0;
 err_invoke:
-	if (fl->cctx->vmcount && scm_done) {
-		u64 src_perms = 0;
-		struct qcom_scm_vmperm dst_perms;
-		u32 i;
-
-		for (i = 0; i < fl->cctx->vmcount; i++)
-			src_perms |= BIT(fl->cctx->vmperms[i].vmid);
-
-		dst_perms.vmid = QCOM_SCM_VMID_HLOS;
-		dst_perms.perm = QCOM_SCM_PERM_RWX;
-		err = qcom_scm_assign_mem(fl->cctx->remote_heap->dma_addr,
-						(u64)fl->cctx->remote_heap->size,
-						&src_perms, &dst_perms, 1);
-		if (err)
-			dev_err(fl->sctx->dev, "Failed to assign memory dma_addr %pad size 0x%llx err %d\n",
-				&fl->cctx->remote_heap->dma_addr, fl->cctx->remote_heap->size, err);
+	if (sent_heap) {
+		spin_lock_irqsave(&cctx->lock, flags);
+		cctx->audio_init_mem = false;
+		spin_unlock_irqrestore(&cctx->lock, flags);
 	}
-err_map:
-	fastrpc_buf_free(fl->cctx->remote_heap);
-	fl->cctx->remote_heap = NULL;
-err_name:
 	kfree(name);
 err:
 	kfree(args);
@@ -2090,7 +2077,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
 	if (copy_from_user(&req, argp, sizeof(req)))
 		return -EFAULT;
 
-	if (req.flags != ADSP_MMAP_ADD_PAGES && req.flags != ADSP_MMAP_REMOTE_HEAP_ADDR) {
+	if (req.flags != ADSP_MMAP_ADD_PAGES) {
 		dev_err(dev, "flag not supported 0x%x\n", req.flags);
 
 		return -EINVAL;
@@ -2101,10 +2088,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
 		return -EINVAL;
 	}
 
-	if (req.flags == ADSP_MMAP_REMOTE_HEAP_ADDR)
-		err = fastrpc_remote_heap_alloc(fl, dev, req.size, &buf);
-	else
-		err = fastrpc_buf_alloc(fl, dev, req.size, &buf);
+	err = fastrpc_buf_alloc(fl, dev, req.size, &buf);
 
 	if (err) {
 		dev_err(dev, "failed to allocate buffer\n");
@@ -2143,20 +2127,6 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
 	/* let the client know the address to use */
 	req.vaddrout = rsp_msg.vaddr;
 
-	/* Add memory to static PD pool, protection thru hypervisor */
-	if (req.flags == ADSP_MMAP_REMOTE_HEAP_ADDR && fl->cctx->vmcount) {
-		u64 src_perms = BIT(QCOM_SCM_VMID_HLOS);
-
-		err = qcom_scm_assign_mem(buf->dma_addr, (u64)buf->size,
-			&src_perms, fl->cctx->vmperms, fl->cctx->vmcount);
-		if (err) {
-			dev_err(fl->sctx->dev,
-				"Failed to assign memory dma_addr %pad size 0x%llx err %d",
-				&buf->dma_addr, buf->size, err);
-			goto err_assign;
-		}
-	}
-
 	spin_lock(&fl->lock);
 	list_add_tail(&buf->node, &fl->mmaps);
 	spin_unlock(&fl->lock);
@@ -2537,6 +2507,45 @@ static const struct of_device_id fastrpc_poll_supported_machines[] __maybe_unuse
 	{},
 };
 
+static int fastrpc_init_reserved_mem(struct fastrpc_channel_ctx *cctx,
+				     struct device *rdev, u32 domain_id)
+{
+	struct resource res;
+	u64 src_perms;
+	int err;
+
+	/* Only SDSP and ADSP domains use a reserved remote heap region */
+	if (domain_id != SDSP_DOMAIN_ID && domain_id != ADSP_DOMAIN_ID)
+		return 0;
+
+	err = of_reserved_mem_region_to_resource(rdev->of_node, 0, &res);
+	if (err) {
+		/*
+		 * The reserved-memory region is optional at probe time. For
+		 * the Audio PD (ADSP) domain its absence is validated later in
+		 * fastrpc_init_create_static_process(), so keep probing here.
+		 */
+		return 0;
+	}
+
+	/*
+	 * Audio PD (ADSP) is a static PD: cache the region so its lifetime
+	 * is tied to the rpmsg channel instead of being controlled by
+	 * userspace.
+	 */
+	if (domain_id == ADSP_DOMAIN_ID) {
+		cctx->remote_heap_addr = res.start;
+		cctx->remote_heap_size = resource_size(&res);
+	}
+
+	if (!cctx->vmcount)
+		return 0;
+
+	src_perms = BIT(QCOM_SCM_VMID_HLOS);
+	return qcom_scm_assign_mem(res.start, resource_size(&res), &src_perms,
+				  cctx->vmperms, cctx->vmcount);
+}
+
 static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 {
 	struct device *rdev = &rpdev->dev;
@@ -2584,21 +2593,9 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 		}
 	}
 
-	if (domain_id == SDSP_DOMAIN_ID) {
-		struct resource res;
-		u64 src_perms;
-
-		err = of_reserved_mem_region_to_resource(rdev->of_node, 0, &res);
-		if (!err) {
-			src_perms = BIT(QCOM_SCM_VMID_HLOS);
-
-			err = qcom_scm_assign_mem(res.start, resource_size(&res), &src_perms,
-				    data->vmperms, data->vmcount);
-			if (err)
-				goto err_free_data;
-		}
-
-	}
+	err = fastrpc_init_reserved_mem(data, rdev, domain_id);
+	if (err)
+		goto err_free_data;
 
 	secure_dsp = !(of_property_read_bool(rdev->of_node, "qcom,non-secure-domain"));
 	data->secure = secure_dsp;
@@ -2698,8 +2695,25 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	list_for_each_entry_safe(buf, b, &cctx->invoke_interrupted_mmaps, node)
 		list_del(&buf->node);
 
-	if (cctx->remote_heap)
-		fastrpc_buf_free(cctx->remote_heap);
+	if (cctx->remote_heap_size && cctx->vmcount) {
+		u64 src_perms = 0;
+		int err, i;
+		struct qcom_scm_vmperm dst_perms;
+
+		for (i = 0; i < cctx->vmcount; i++)
+			src_perms |= BIT(cctx->vmperms[i].vmid);
+
+		dst_perms.vmid = QCOM_SCM_VMID_HLOS;
+		dst_perms.perm = QCOM_SCM_PERM_RWX;
+
+		err = qcom_scm_assign_mem(cctx->remote_heap_addr,
+					  cctx->remote_heap_size, &src_perms,
+					  &dst_perms, 1);
+		if (err)
+			dev_err(&rpdev->dev,
+				"Failed to assign memory back to HLOS: addr %pa size %#llx err %d\n",
+				&cctx->remote_heap_addr, cctx->remote_heap_size, err);
+	}
 
 	of_platform_depopulate(&rpdev->dev);
 
-- 
2.53.0

Re: [PATCH 0/2] misc: fastrpc: fixes for 7.3

[Greg KH]

On Fri, Oct 02, 2026 at 11:12:18AM +0100, Srinivas Kandagatla wrote:
> From: Srinivas Kandagatla <srini@kernel.org>
> 
> Hi Greg,
> 
> Here are few fastrpc fixes for 7.3, Could you please queue
> these for 7.3.
> 
> Patches include
> 	- fix double-free in fastrpc_map_attach() error path
> 	- allocate entire Audio PD reserved memory in probe to avoid
> 	  userspace-controlled alloc/free and unbounded heap growth
> 
> Thanks,
> Srini
> 
> Jianping Li (1):
>   misc: fastrpc: Allocate entire reserved memory for Audio PD in probe
> 
> Yifei Gao (1):
>   misc: fastrpc: fix double-free in fastrpc_map_attach() error path
> 
>  drivers/misc/fastrpc.c | 192 ++++++++++++++++++++++-------------------
>  1 file changed, 103 insertions(+), 89 deletions(-)
> 
> -- 
> 2.53.0
> 

I'll take these for -rc1 sorry for the delay.
greg k-h