[PATCH v5 1/1] soc: qcom: mdt_loader: Enhance split binary detection

[Gokul krishna Krishnakumar]

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 to fail for split bins.
This change updates the logic used by the mdt loader to understand whether
the firmware images are split or not. It figures this out 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>
---
V5: Removes extra empty lines from V4.

V4: Removes the unneceessary change in qcom_mdt_read_metadata(), the
exisiting check holds good in case the hash segment is in the loaded image.

V3 is separated out from [1] and includes
changes addressing comments from that patch set.

[1] https://lore.kernel.org/all/20230306231202.12223-5-quic_molvera@xxxxxxxxxxx/
---
 drivers/soc/qcom/mdt_loader.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index 33dd8c315eb7..814646ce41e5 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -258,6 +258,26 @@ int qcom_mdt_pas_init(struct device *dev, const struct firmware *fw,
 }
 EXPORT_SYMBOL_GPL(qcom_mdt_pas_init);
 
+static bool qcom_mdt_bins_are_split(const struct firmware *fw, const char* fw_name)
+{
+	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 int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 			   const char *fw_name, int pas_id, void *mem_region,
 			   phys_addr_t mem_phys, size_t mem_size,
@@ -270,6 +290,7 @@ 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 +298,7 @@ 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, fw_name);
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);
 
@@ -330,8 +352,7 @@ 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) {
+		if (phdr->p_filesz && !is_split) {
 			/* 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",
-- 
2.39.2