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Date:   Tue,  5 Oct 2021 15:02:45 +0530
From:   Deepak Kumar Singh <deesin@...eaurora.org>
To:     bjorn.andersson@...aro.org, clew@...eaurora.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org,
        Deepak Kumar Singh <deesin@...eaurora.org>,
        Andy Gross <agross@...nel.org>
Subject: [PATCH V3 2/2] soc: qcom: smem: validate fields of shared structures

Structures in shared memory that can be modified by remote
processors may have untrusted values, they should be validated
before use.

Adding proper validation before using fields of shared
structures.

Signed-off-by: Deepak Kumar Singh <deesin@...eaurora.org>
---
 drivers/soc/qcom/smem.c | 79 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 69 insertions(+), 10 deletions(-)

diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index dfbd06b..5cd3ddb 100644
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -366,13 +366,18 @@ static int qcom_smem_alloc_private(struct qcom_smem *smem,
 	struct smem_partition_header *phdr;
 	size_t alloc_size;
 	void *cached;
+	void *p_end;
 
 	phdr = (struct smem_partition_header __force *)part->virt_base;
+	p_end = (void *)phdr + part->size;
 
 	hdr = phdr_to_first_uncached_entry(phdr);
 	end = phdr_to_last_uncached_entry(phdr);
 	cached = phdr_to_last_cached_entry(phdr);
 
+	if (WARN_ON((void *)end > p_end || (void *)cached > p_end))
+		return -EINVAL;
+
 	while (hdr < end) {
 		if (hdr->canary != SMEM_PRIVATE_CANARY)
 			goto bad_canary;
@@ -382,6 +387,9 @@ static int qcom_smem_alloc_private(struct qcom_smem *smem,
 		hdr = uncached_entry_next(hdr);
 	}
 
+	if (WARN_ON((void *)hdr > p_end))
+		return -EINVAL;
+
 	/* Check that we don't grow into the cached region */
 	alloc_size = sizeof(*hdr) + ALIGN(size, 8);
 	if ((void *)hdr + alloc_size > cached) {
@@ -500,6 +508,8 @@ static void *qcom_smem_get_global(struct qcom_smem *smem,
 	struct smem_header *header;
 	struct smem_region *region;
 	struct smem_global_entry *entry;
+	u64 entry_offset;
+	u32 e_size;
 	u32 aux_base;
 	unsigned i;
 
@@ -514,9 +524,16 @@ static void *qcom_smem_get_global(struct qcom_smem *smem,
 		region = &smem->regions[i];
 
 		if (region->aux_base == aux_base || !aux_base) {
+			e_size = le32_to_cpu(entry->size);
+			entry_offset = le32_to_cpu(entry->offset);
+
+			if (WARN_ON(e_size + entry_offset > region->size))
+				return ERR_PTR(-EINVAL);
+
 			if (size != NULL)
-				*size = le32_to_cpu(entry->size);
-			return region->virt_base + le32_to_cpu(entry->offset);
+				*size = e_size;
+
+			return region->virt_base + entry_offset;
 		}
 	}
 
@@ -530,8 +547,12 @@ static void *qcom_smem_get_private(struct qcom_smem *smem,
 {
 	struct smem_private_entry *e, *end;
 	struct smem_partition_header *phdr;
+	void *item_ptr, *p_end;
+	u32 padding_data;
+	u32 e_size;
 
 	phdr = (struct smem_partition_header __force *)part->virt_base;
+	p_end = (void *)phdr + part->size;
 
 	e = phdr_to_first_uncached_entry(phdr);
 	end = phdr_to_last_uncached_entry(phdr);
@@ -541,36 +562,65 @@ static void *qcom_smem_get_private(struct qcom_smem *smem,
 			goto invalid_canary;
 
 		if (le16_to_cpu(e->item) == item) {
-			if (size != NULL)
-				*size = le32_to_cpu(e->size) -
-					le16_to_cpu(e->padding_data);
+			if (size != NULL) {
+				e_size = le32_to_cpu(e->size);
+				padding_data = le16_to_cpu(e->padding_data);
+
+				if (WARN_ON(e_size > part->size || padding_data > e_size))
+					return ERR_PTR(-EINVAL);
+
+				*size = e_size - padding_data;
+			}
+
+			item_ptr = uncached_entry_to_item(e);
+			if (WARN_ON(item_ptr > p_end))
+				return ERR_PTR(-EINVAL);
 
-			return uncached_entry_to_item(e);
+			return item_ptr;
 		}
 
 		e = uncached_entry_next(e);
 	}
 
+	if (WARN_ON((void *)e > p_end))
+		return ERR_PTR(-EINVAL);
+
 	/* Item was not found in the uncached list, search the cached list */
 
 	e = phdr_to_first_cached_entry(phdr, part->cacheline);
 	end = phdr_to_last_cached_entry(phdr);
 
+	if (WARN_ON((void *)e < (void *)phdr || (void *)end > p_end))
+		return ERR_PTR(-EINVAL);
+
 	while (e > end) {
 		if (e->canary != SMEM_PRIVATE_CANARY)
 			goto invalid_canary;
 
 		if (le16_to_cpu(e->item) == item) {
-			if (size != NULL)
-				*size = le32_to_cpu(e->size) -
-					le16_to_cpu(e->padding_data);
+			if (size != NULL) {
+				e_size = le32_to_cpu(e->size);
+				padding_data = le16_to_cpu(e->padding_data);
+
+				if (WARN_ON(e_size > part->size || padding_data > e_size))
+					return ERR_PTR(-EINVAL);
+
+				*size = e_size - padding_data;
+			}
 
-			return cached_entry_to_item(e);
+			item_ptr = cached_entry_to_item(e);
+			if (WARN_ON(item_ptr < (void *)phdr))
+				return ERR_PTR(-EINVAL);
+
+			return item_ptr;
 		}
 
 		e = cached_entry_next(e, part->cacheline);
 	}
 
+	if (WARN_ON((void *)e < (void *)phdr))
+		return ERR_PTR(-EINVAL);
+
 	return ERR_PTR(-ENOENT);
 
 invalid_canary:
@@ -647,14 +697,23 @@ int qcom_smem_get_free_space(unsigned host)
 		phdr = part->virt_base;
 		ret = le32_to_cpu(phdr->offset_free_cached) -
 		      le32_to_cpu(phdr->offset_free_uncached);
+
+		if (ret > le32_to_cpu(part->size))
+			return -EINVAL;
 	} else if (__smem->global_partition.virt_base) {
 		part = &__smem->global_partition;
 		phdr = part->virt_base;
 		ret = le32_to_cpu(phdr->offset_free_cached) -
 		      le32_to_cpu(phdr->offset_free_uncached);
+
+		if (ret > le32_to_cpu(part->size))
+			return -EINVAL;
 	} else {
 		header = __smem->regions[0].virt_base;
 		ret = le32_to_cpu(header->available);
+
+		if (ret > __smem->regions[0].size)
+			return -EINVAL;
 	}
 
 	return ret;
-- 
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a Linux Foundation Collaborative Project

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