[PATCH AUTOSEL 6.16 77/85] soc: qcom: mdt_loader: Actually use the e_phoff

[Sasha Levin <sashal@kernel.org>]

From: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>

[ Upstream commit 47e339cac89143709e84a3b71ba8bd9b2fdd2368 ]

Rather than relying/assuming that the tools generating the firmware
places the program headers immediately following the ELF header, use
e_phoff as intended to find the program headers.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250610-mdt-loader-validation-and-fixes-v2-3-f7073e9ab899@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

Based on my analysis of the commit and code changes, I can now provide
my assessment:

**Backport Status: YES**

This commit should be backported to stable kernel trees for the
following reasons:

1. **Bug Fix**: The commit fixes a genuine bug where the code was
   incorrectly assuming that program headers immediately follow the ELF
   header instead of using the `e_phoff` (ELF header's program header
   offset) field. This is a clear violation of the ELF specification.

2. **Security Implications**: The bug could lead to incorrect parsing of
   firmware files, potentially causing:
   - Out-of-bounds memory access if `e_phoff` points to a location
     beyond `sizeof(ehdr)`
   - Loading incorrect data as program headers
   - Firmware loading failures or crashes in Qualcomm devices

3. **Minimal Risk**: The fix is simple and contained - it changes 4
   lines in the same pattern:
  ```c
   - phdrs = (struct elf32_phdr *)(ehdr + 1);
   + phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
   ```

4. **Affects Multiple Functions**: The bug affects critical firmware
   loading functions:
   - `qcom_mdt_get_size()` - calculates memory requirements
   - `qcom_mdt_read_metadata()` - reads firmware metadata for
     authentication
   - `qcom_mdt_pas_init()` - initializes firmware loading
   - `qcom_mdt_bins_are_split()` - determines firmware structure
   - `__qcom_mdt_load()` - performs actual firmware loading

5. **Real-World Impact**: This affects Qualcomm device firmware loading,
   which is used in many Android devices and embedded systems. Incorrect
   firmware loading could lead to device failures.

6. **Clear Fix**: The commit message clearly explains the issue and the
   fix follows ELF specification standards by properly using `e_phoff`
   instead of making assumptions about file layout.

7. **Stable Tree Criteria Met**:
   - Fixes a real bug that affects users
   - Small, self-contained change
   - No architectural changes
   - Low risk of regression
   - Important for device stability

The fix ensures proper ELF parsing according to specification and
prevents potential security issues from incorrect memory access during
firmware loading on Qualcomm platforms.

 drivers/soc/qcom/mdt_loader.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index b2c0fb55d4ae..44589d10b15b 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -83,7 +83,7 @@ ssize_t qcom_mdt_get_size(const struct firmware *fw)
 	int i;
 
 	ehdr = (struct elf32_hdr *)fw->data;
-	phdrs = (struct elf32_phdr *)(ehdr + 1);
+	phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
 
 	for (i = 0; i < ehdr->e_phnum; i++) {
 		phdr = &phdrs[i];
@@ -135,7 +135,7 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
 	void *data;
 
 	ehdr = (struct elf32_hdr *)fw->data;
-	phdrs = (struct elf32_phdr *)(ehdr + 1);
+	phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
 
 	if (ehdr->e_phnum < 2)
 		return ERR_PTR(-EINVAL);
@@ -215,7 +215,7 @@ int qcom_mdt_pas_init(struct device *dev, const struct firmware *fw,
 	int i;
 
 	ehdr = (struct elf32_hdr *)fw->data;
-	phdrs = (struct elf32_phdr *)(ehdr + 1);
+	phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
 
 	for (i = 0; i < ehdr->e_phnum; i++) {
 		phdr = &phdrs[i];
@@ -270,7 +270,7 @@ static bool qcom_mdt_bins_are_split(const struct firmware *fw, const char *fw_na
 	int i;
 
 	ehdr = (struct elf32_hdr *)fw->data;
-	phdrs = (struct elf32_phdr *)(ehdr + 1);
+	phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
 
 	for (i = 0; i < ehdr->e_phnum; i++) {
 		/*
@@ -312,7 +312,7 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 
 	is_split = qcom_mdt_bins_are_split(fw, fw_name);
 	ehdr = (struct elf32_hdr *)fw->data;
-	phdrs = (struct elf32_phdr *)(ehdr + 1);
+	phdrs = (struct elf32_phdr *)(fw->data + ehdr->e_phoff);
 
 	for (i = 0; i < ehdr->e_phnum; i++) {
 		phdr = &phdrs[i];
-- 
2.39.5