[PATCH v2 4/7] soc: qcom: mdt_loader: Enhance split binary detection

[Melody Olvera <quic_molvera@xxxxxxxxxxx>]

From: Gokul Krishna Krishnakumar <quic_gokukris@xxxxxxxxxxx>

When booting with split binaries, it may be that the offset of the first
program header lies inside the mdt's filesize, in this case the loader
would incorrectly assume that the bins were not split. The loading would
then continue on and fail for split bins. This change updates the logic used
by the mdt loader to understand whether the firmware images are split or not
by checking if each programs header's segment lies within the file or not.

Signed-off-by: Gokul Krishna Krishnakumar <quic_gokukris@xxxxxxxxxxx>
Signed-off-by: Melody Olvera <quic_molvera@xxxxxxxxxxx>
---
 drivers/soc/qcom/mdt_loader.c | 64 +++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 29 deletions(-)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index 33dd8c315eb7..3aadce299c02 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -31,6 +31,26 @@ static bool mdt_phdr_valid(const struct elf32_phdr *phdr)
 	return true;
 }
 
+static bool qcom_mdt_bins_are_split(const struct firmware *fw)
+{
+	const struct elf32_phdr *phdrs;
+	const struct elf32_hdr *ehdr;
+	uint64_t seg_start, seg_end;
+	int i;
+
+	ehdr = (struct elf32_hdr *)fw->data;
+	phdrs = (struct elf32_phdr *)(ehdr + 1);
+
+	for (i = 0; i < ehdr->e_phnum; i++) {
+		seg_start = phdrs[i].p_offset;
+		seg_end = phdrs[i].p_offset + phdrs[i].p_filesz;
+		if (seg_start > fw->size || seg_end > fw->size)
+			return true;
+	}
+
+	return false;
+}
+
 static ssize_t mdt_load_split_segment(void *ptr, const struct elf32_phdr *phdrs,
 				      unsigned int segment, const char *fw_name,
 				      struct device *dev)
@@ -167,23 +187,13 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
 	/* Copy ELF header */
 	memcpy(data, fw->data, ehdr_size);
 
-	if (ehdr_size + hash_size == fw->size) {
-		/* Firmware is split and hash is packed following the ELF header */
-		hash_offset = phdrs[0].p_filesz;
-		memcpy(data + ehdr_size, fw->data + hash_offset, hash_size);
-	} else if (phdrs[hash_segment].p_offset + hash_size <= fw->size) {
-		/* Hash is in its own segment, but within the loaded file */
+
+	if (qcom_mdt_bins_are_split(fw)) {
+		ret = mdt_load_split_segment(data + ehdr_size, phdrs, hash_segment, fw_name, dev);
+	} else {
 		hash_offset = phdrs[hash_segment].p_offset;
 		memcpy(data + ehdr_size, fw->data + hash_offset, hash_size);
-	} else {
-		/* Hash is in its own segment, beyond the loaded file */
-		ret = mdt_load_split_segment(data + ehdr_size, phdrs, hash_segment, fw_name, dev);
-		if (ret) {
-			kfree(data);
-			return ERR_PTR(ret);
-		}
 	}
-
 	*data_len = ehdr_size + hash_size;
 
 	return data;
@@ -270,6 +280,7 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 	phys_addr_t min_addr = PHYS_ADDR_MAX;
 	ssize_t offset;
 	bool relocate = false;
+	bool is_split;
 	void *ptr;
 	int ret = 0;
 	int i;
@@ -277,6 +288,7 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 	if (!fw || !mem_region || !mem_phys || !mem_size)
 		return -EINVAL;
 
+	is_split = qcom_mdt_bins_are_split(fw);
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);
 
@@ -330,22 +342,16 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 
 		ptr = mem_region + offset;
 
-		if (phdr->p_filesz && phdr->p_offset < fw->size &&
-		    phdr->p_offset + phdr->p_filesz <= fw->size) {
-			/* Firmware is large enough to be non-split */
-			if (phdr->p_offset + phdr->p_filesz > fw->size) {
-				dev_err(dev, "file %s segment %d would be truncated\n",
-					fw_name, i);
-				ret = -EINVAL;
-				break;
+		if (phdr->p_filesz) {
+			if (!is_split) {
+				/* Firmware is large enough to be non-split */
+				memcpy(ptr, fw->data + phdr->p_offset, phdr->p_filesz);
+			} else {
+				/* Firmware not large enough, load split-out segments */
+				ret = mdt_load_split_segment(ptr, phdrs, i, fw_name, dev);
+				if (ret)
+					break;
 			}
-
-			memcpy(ptr, fw->data + phdr->p_offset, phdr->p_filesz);
-		} else if (phdr->p_filesz) {
-			/* Firmware not large enough, load split-out segments */
-			ret = mdt_load_split_segment(ptr, phdrs, i, fw_name, dev);
-			if (ret)
-				break;
 		}
 
 		if (phdr->p_memsz > phdr->p_filesz)
-- 
2.25.1