[PATCH 1/3] soc: qcom: mdt_loader: Ensure we don't read past the ELF header

[Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>]

When the MDT loader is used in remoteproc, the ELF header is sanitized
beforehand, but that's not necessary the case for other clients.

Validate the size of the firmware buffer to ensure that we don't read
past the end as we iterate over the header.

Fixes: 2aad40d911ee ("remoteproc: Move qcom_mdt_loader into drivers/soc/qcom")
Cc: <stable@vger.kernel.org>
Reported-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
---
 drivers/soc/qcom/mdt_loader.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index b2c0fb55d4ae678ee333f0d6b8b586de319f53b1..1da22b23d19d28678ec78cccdf8c328b50d3ffda 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -18,6 +18,31 @@
 #include <linux/slab.h>
 #include <linux/soc/qcom/mdt_loader.h>
 
+static bool mdt_header_valid(const struct firmware *fw)
+{
+	const struct elf32_hdr *ehdr;
+	size_t phend;
+	size_t shend;
+
+	if (fw->size < sizeof(*ehdr))
+		return false;
+
+	ehdr = (struct elf32_hdr *)fw->data;
+
+	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG))
+		return false;
+
+	phend = size_add(size_mul(sizeof(struct elf32_phdr), ehdr->e_phnum), ehdr->e_phoff);
+	if (phend > fw->size)
+		return false;
+
+	shend = size_add(size_mul(sizeof(struct elf32_shdr), ehdr->e_shnum), ehdr->e_shoff);
+	if (shend > fw->size)
+		return false;
+
+	return true;
+}
+
 static bool mdt_phdr_valid(const struct elf32_phdr *phdr)
 {
 	if (phdr->p_type != PT_LOAD)
@@ -82,6 +107,9 @@ ssize_t qcom_mdt_get_size(const struct firmware *fw)
 	phys_addr_t max_addr = 0;
 	int i;
 
+	if (!mdt_header_valid(fw))
+		return -EINVAL;
+
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);
 
@@ -134,6 +162,9 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
 	ssize_t ret;
 	void *data;
 
+	if (!mdt_header_valid(fw))
+		return ERR_PTR(-EINVAL);
+
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);
 
@@ -214,6 +245,9 @@ int qcom_mdt_pas_init(struct device *dev, const struct firmware *fw,
 	int ret;
 	int i;
 
+	if (!mdt_header_valid(fw))
+		return -EINVAL;
+
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);
 
@@ -310,6 +344,9 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 	if (!fw || !mem_region || !mem_phys || !mem_size)
 		return -EINVAL;
 
+	if (!mdt_header_valid(fw))
+		return -EINVAL;
+
 	is_split = qcom_mdt_bins_are_split(fw, fw_name);
 	ehdr = (struct elf32_hdr *)fw->data;
 	phdrs = (struct elf32_phdr *)(ehdr + 1);

-- 
2.49.0