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Subject[PATCH 5/7] remoteproc: look for truncated firmware images
Date
Make sure firmware isn't truncated before accessing its data.

Reported-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
---
drivers/remoteproc/remoteproc_core.c | 35 +++++++++++++++++++++++++++++----
1 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 080c056..f2354ce 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -191,6 +191,7 @@ static void *rproc_da_to_va(struct rproc *rproc, u64 da, int len)
* rproc_load_segments() - load firmware segments to memory
* @rproc: remote processor which will be booted using these fw segments
* @elf_data: the content of the ELF firmware image
+ * @len: firmware size (in bytes)
*
* This function loads the firmware segments to memory, where the remote
* processor expects them.
@@ -211,7 +212,8 @@ static void *rproc_da_to_va(struct rproc *rproc, u64 da, int len)
* directly allocate memory for every segment/resource. This is not yet
* supported, though.
*/
-static int rproc_load_segments(struct rproc *rproc, const u8 *elf_data)
+static int
+rproc_load_segments(struct rproc *rproc, const u8 *elf_data, size_t len)
{
struct device *dev = rproc->dev;
struct elf32_hdr *ehdr;
@@ -226,6 +228,7 @@ static int rproc_load_segments(struct rproc *rproc, const u8 *elf_data)
u32 da = phdr->p_paddr;
u32 memsz = phdr->p_memsz;
u32 filesz = phdr->p_filesz;
+ u32 offset = phdr->p_offset;
void *ptr;

if (phdr->p_type != PT_LOAD)
@@ -241,6 +244,13 @@ static int rproc_load_segments(struct rproc *rproc, const u8 *elf_data)
break;
}

+ if (offset + filesz > len) {
+ dev_err(dev, "truncated fw: need 0x%x avail 0x%x\n",
+ offset + filesz, len);
+ ret = -EINVAL;
+ break;
+ }
+
/* grab the kernel address for this device address */
ptr = rproc_da_to_va(rproc, da, memsz);
if (!ptr) {
@@ -712,6 +722,7 @@ rproc_handle_virtio_rsc(struct rproc *rproc, struct fw_resource *rsc, int len)
* rproc_handle_resources() - find and handle the resource table
* @rproc: the rproc handle
* @elf_data: the content of the ELF firmware image
+ * @len: firmware size (in bytes)
* @handler: function that should be used to handle the resource table
*
* This function finds the resource table inside the remote processor's
@@ -725,7 +736,7 @@ rproc_handle_virtio_rsc(struct rproc *rproc, struct fw_resource *rsc, int len)
* processors that don't need a resource table.
*/
static int rproc_handle_resources(struct rproc *rproc, const u8 *elf_data,
- rproc_handle_resources_t handler)
+ size_t len, rproc_handle_resources_t handler)

{
struct elf32_hdr *ehdr;
@@ -743,6 +754,13 @@ static int rproc_handle_resources(struct rproc *rproc, const u8 *elf_data,
struct fw_resource *table = (struct fw_resource *)
(elf_data + shdr->sh_offset);

+ if (shdr->sh_offset + shdr->sh_size > len) {
+ dev_err(rproc->dev,
+ "truncated fw: need 0x%x avail 0x%x\n",
+ shdr->sh_offset + shdr->sh_size, len);
+ ret = -EINVAL;
+ }
+
ret = handler(rproc, table, shdr->sh_size);

break;
@@ -833,6 +851,11 @@ static int rproc_fw_sanity_check(struct rproc *rproc, const struct firmware *fw)

ehdr = (struct elf32_hdr *)fw->data;

+ if (fw->size < ehdr->e_shoff + sizeof(struct elf32_shdr)) {
+ dev_err(dev, "Image is too small\n");
+ return -EINVAL;
+ }
+
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG)) {
dev_err(dev, "Image is corrupted (bad magic)\n");
return -EINVAL;
@@ -887,14 +910,15 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
rproc->bootaddr = ehdr->e_entry;

/* handle fw resources which are required to boot rproc */
- ret = rproc_handle_resources(rproc, fw->data, rproc_handle_boot_rsc);
+ ret = rproc_handle_resources(rproc, fw->data, fw->size,
+ rproc_handle_boot_rsc);
if (ret) {
dev_err(dev, "Failed to process resources: %d\n", ret);
goto clean_up;
}

/* load the ELF segments to memory */
- ret = rproc_load_segments(rproc, fw->data);
+ ret = rproc_load_segments(rproc, fw->data, fw->size);
if (ret) {
dev_err(dev, "Failed to load program segments: %d\n", ret);
goto clean_up;
@@ -937,7 +961,8 @@ static void rproc_fw_config_virtio(const struct firmware *fw, void *context)
goto out;

/* does the fw supports any virtio devices ? */
- ret = rproc_handle_resources(rproc, fw->data, rproc_handle_virtio_rsc);
+ ret = rproc_handle_resources(rproc, fw->data, fw->size,
+ rproc_handle_virtio_rsc);
if (ret) {
dev_info(dev, "No fw virtio device was found\n");
goto out;
--
1.7.5.4


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