The integrity of the struct module we load is important, and although
our ELF validator already checks that the module section must match
struct module, add a stop-gap check before we memcpy() the final minted
module. This also makes those inspecting the code what the goal is.
While at it, clarify the goal behind updating the sh_addr address.
The current comment is pretty misleading.
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
kernel/module/main.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c
index e1a9dd51c036..fbe62d1625bc 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2213,7 +2213,8 @@ static int move_module(struct module *mod, struct load_info *info)
{
int i;
void *ptr;
- enum mod_mem_type t;
+ enum mod_mem_type t = 0;
+ int ret = -ENOMEM;
for_each_mod_mem_type(type) {
if (!mod->mem[type].size) {
@@ -2249,9 +2250,26 @@ static int move_module(struct module *mod, struct load_info *info)
dest = mod->mem[type].base + (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK);
- if (shdr->sh_type != SHT_NOBITS)
+ if (shdr->sh_type != SHT_NOBITS) {
+ /*
+ * Our ELF checker already validated this, but let's
+ * be pedantic and make the goal clearer. We actually
+ * end up copying over all modifications made to the
+ * userspace copy of the entire struct module.
+ */
+ if (i == info->index.mod &&
+ (WARN_ON_ONCE(shdr->sh_size != sizeof(struct module)))) {
+ ret = -ENOEXEC;
+ goto out_enomem;
+ }
memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
- /* Update sh_addr to point to copy in image. */
+ }
+ /*
+ * Update the userspace copy's ELF section address to point to
+ * our newly allocated memory as a pure convenience so that
+ * users of info can keep taking advantage and using the newly
+ * minted official memory area.
+ */
shdr->sh_addr = (unsigned long)dest;
pr_debug("\t0x%lx %s\n",
(long)shdr->sh_addr, info->secstrings + shdr->sh_name);
@@ -2261,7 +2279,7 @@ static int move_module(struct module *mod, struct load_info *info)
out_enomem:
for (t--; t >= 0; t--)
module_memory_free(mod->mem[t].base, t);
- return -ENOMEM;
+ return ret;
}
static int check_export_symbol_versions(struct module *mod)
--
2.39.1
