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-f707... 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];