[PATCH] soc: qcom: geni-se: Fix write to read-only firmware buffer

[Viken Dadhaniya]

geni_find_protocol_fw() casts fw->data to a non-const struct se_fw_hdr
pointer and writes back a rounded-up fw_size value:

        sefw->fw_size_in_items = cpu_to_le16(fw_size);

The firmware subsystem maps the firmware blob read-only. Writing through
the cast pointer causes a level-3 permission fault on AArch64 and
crashes the kernel during driver probe.

Remove the write-back. fw_size is u16, so incrementing 0xffff wraps
to 0, letting the bounds check pass for an unchecked size; widen it to
u32. The bounds check used the unrounded fw_size, so a segment with an
odd word count can pass validation but trigger an out-of-bounds read
during the copy; round up before computing fw_end. The caller re-reads
fw_size_in_items directly, bypassing the validated value; propagate it
via a new fw_size_out parameter.

While at it, fix serial_protocol being compared with le32_to_cpu();
the field is __le16, which would cause the protocol match to always
fail on big-endian.

Fixes: d4bf06592ad6 ("soc: qcom: geni-se: Add support to load QUP SE Firmware via Linux subsystem")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@xxxxxxxxxxxxxxxx>
---
 drivers/soc/qcom/qcom-geni-se.c | 46 ++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
index 873bfbd6b2b7..16f7af8a33d4 100644
--- a/drivers/soc/qcom/qcom-geni-se.c
+++ b/drivers/soc/qcom/qcom-geni-se.c
@@ -1230,25 +1230,28 @@ EXPORT_SYMBOL_GPL(geni_se_resources_init);
  * @se: Pointer to the serial engine structure.
  * @fw: Pointer to the firmware image.
  * @protocol: Expected serial engine protocol type.
+ * @fw_size_out: Non-NULL output parameter; receives the rounded, validated
+ *               firmware word count on success.
  *
  * Identifies the appropriate firmware image or configuration required for a
  * specific communication protocol instance running on a Qualcomm GENI
  * controller. Validates the firmware size against the hardware PROG_RAM_DEPTH
  * read from SE_HW_PARAM_2.
  *
- * Return: pointer to a valid 'struct se_fw_hdr' if found, or NULL otherwise.
+ * Return: pointer to a valid 'const struct se_fw_hdr' if found, or NULL otherwise.
  */
-static struct se_fw_hdr *geni_find_protocol_fw(struct geni_se *se, const struct firmware *fw,
-					       enum geni_se_protocol_type protocol)
+static const struct se_fw_hdr *geni_find_protocol_fw(struct geni_se *se, const struct firmware *fw,
+						     enum geni_se_protocol_type protocol,
+						     u32 *fw_size_out)
 {
 	struct device *dev = se->dev;
 	const struct elf32_hdr *ehdr;
 	const struct elf32_phdr *phdrs;
 	const struct elf32_phdr	*phdr;
-	struct se_fw_hdr *sefw;
+	const struct se_fw_hdr *sefw;
 	u32 fw_end, cfg_idx_end, cfg_val_end;
 	u32 prog_ram_depth;
-	u16 fw_size;
+	u32 fw_size;
 	int i;
 
 	if (!fw || fw->size < sizeof(struct elf32_hdr))
@@ -1287,24 +1290,24 @@ static struct se_fw_hdr *geni_find_protocol_fw(struct geni_se *se, const struct
 		if (phdr->p_filesz < sizeof(struct se_fw_hdr))
 			continue;
 
-		sefw = (struct se_fw_hdr *)(fw->data + phdr->p_offset);
+		sefw = (const struct se_fw_hdr *)(fw->data + phdr->p_offset);
 		fw_size = le16_to_cpu(sefw->fw_size_in_items);
-		fw_end = le16_to_cpu(sefw->fw_offset) + fw_size * sizeof(u32);
-		cfg_idx_end = le16_to_cpu(sefw->cfg_idx_offset) +
-			      le16_to_cpu(sefw->cfg_size_in_items) * sizeof(u8);
-		cfg_val_end = le16_to_cpu(sefw->cfg_val_offset) +
-			      le16_to_cpu(sefw->cfg_size_in_items) * sizeof(u32);
 
 		if (le32_to_cpu(sefw->magic) != SE_MAGIC_NUM || le32_to_cpu(sefw->version) != 1)
 			continue;
 
-		if (le32_to_cpu(sefw->serial_protocol) != protocol)
+		if (le16_to_cpu(sefw->serial_protocol) != protocol)
 			continue;
 
-		if (fw_size % 2 != 0) {
+		/* Round up so fw_end covers the full copy range. */
+		if (fw_size % 2 != 0)
 			fw_size++;
-			sefw->fw_size_in_items = cpu_to_le16(fw_size);
-		}
+
+		fw_end = le16_to_cpu(sefw->fw_offset) + fw_size * sizeof(u32);
+		cfg_idx_end = le16_to_cpu(sefw->cfg_idx_offset) +
+			      le16_to_cpu(sefw->cfg_size_in_items) * sizeof(u8);
+		cfg_val_end = le16_to_cpu(sefw->cfg_val_offset) +
+			      le16_to_cpu(sefw->cfg_size_in_items) * sizeof(u32);
 
 		prog_ram_depth = FIELD_GET(PROG_RAM_DEPTH_MSK,
 					   readl_relaxed(se->base + SE_HW_PARAM_2));
@@ -1320,6 +1323,7 @@ static struct se_fw_hdr *geni_find_protocol_fw(struct geni_se *se, const struct
 			continue;
 		}
 
+		*fw_size_out = fw_size;
 		return sefw;
 	}
 
@@ -1430,17 +1434,17 @@ static int geni_load_se_fw(struct geni_se *se, const struct firmware *fw,
 {
 	const u32 *fw_data, *cfg_val_arr;
 	const u8 *cfg_idx_arr;
-	u32 i, reg_value;
+	u32 i, reg_value, fw_size_in_items;
 	int ret;
-	struct se_fw_hdr *hdr;
+	const struct se_fw_hdr *hdr;
 
-	hdr = geni_find_protocol_fw(se, fw, protocol);
+	hdr = geni_find_protocol_fw(se, fw, protocol, &fw_size_in_items);
 	if (!hdr)
 		return -EINVAL;
 
-	fw_data = (const u32 *)((u8 *)hdr + le16_to_cpu(hdr->fw_offset));
+	fw_data = (const u32 *)((const u8 *)hdr + le16_to_cpu(hdr->fw_offset));
 	cfg_idx_arr = (const u8 *)hdr + le16_to_cpu(hdr->cfg_idx_offset);
-	cfg_val_arr = (const u32 *)((u8 *)hdr + le16_to_cpu(hdr->cfg_val_offset));
+	cfg_val_arr = (const u32 *)((const u8 *)hdr + le16_to_cpu(hdr->cfg_val_offset));
 
 	ret = geni_icc_set_bw(se);
 	if (ret)
@@ -1511,7 +1515,7 @@ static int geni_load_se_fw(struct geni_se *se, const struct firmware *fw,
 
 	/* Program RAM address space. */
 	memcpy_toio(se->base + SE_GENI_CFG_RAMN, fw_data,
-		    le16_to_cpu(hdr->fw_size_in_items) * sizeof(u32));
+		    fw_size_in_items * sizeof(u32));
 
 	/* Put default values on GENI's output pads. */
 	writel_relaxed(0x1, se->base + GENI_FORCE_DEFAULT_REG);

---
base-commit: e6664f2b33db9b6811eb4cec109f06cb2b4f458d
change-id: 20260819-fix-write-to-read-only-firmware-buffer-39ca7834e310

Best regards,
--  
Viken Dadhaniya <viken.dadhaniya@xxxxxxxxxxxxxxxx>