kmemleak: Add modules support

This patch handles the kmemleak operations needed for modules loading so
that memory allocations from inside a module are properly tracked.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 2383e60fcf3f..5cd55ab15daf 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -53,6 +53,7 @@
 #include <linux/ftrace.h>
 #include <linux/async.h>
 #include <linux/percpu.h>
+#include <linux/kmemleak.h>
 
 #if 0
 #define DEBUGP printk
@@ -430,6 +431,7 @@ static void *percpu_modalloc(unsigned long size, unsigned long align,
         unsigned long extra;
         unsigned int i;
         void *ptr;
+        int cpu;
 
         if (align > PAGE_SIZE) {
                 printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
@@ -459,6 +461,11 @@ static void *percpu_modalloc(unsigned long size, unsigned long align,
                         if (!split_block(i, size))
                                 return NULL;
 
+                /* add the per-cpu scanning areas */
+                for_each_possible_cpu(cpu)
+                        kmemleak_alloc(ptr + per_cpu_offset(cpu), size, 0,
+                                       GFP_KERNEL);
+
                 /* Mark allocated */
                 pcpu_size[i] = -pcpu_size[i];
                 return ptr;
@@ -473,6 +480,7 @@ static void percpu_modfree(void *freeme)
 {
         unsigned int i;
         void *ptr = __per_cpu_start + block_size(pcpu_size[0]);
+        int cpu;
 
         /* First entry is core kernel percpu data. */
         for (i = 1; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
@@ -484,6 +492,10 @@ static void percpu_modfree(void *freeme)
         BUG();
 
  free:
+        /* remove the per-cpu scanning areas */
+        for_each_possible_cpu(cpu)
+                kmemleak_free(freeme + per_cpu_offset(cpu));
+
         /* Merge with previous? */
         if (pcpu_size[i-1] >= 0) {
                 pcpu_size[i-1] += pcpu_size[i];
@@ -1876,6 +1888,36 @@ static void *module_alloc_update_bounds(unsigned long size)
         return ret;
 }
 
+#ifdef CONFIG_DEBUG_KMEMLEAK
+static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
+                                 Elf_Shdr *sechdrs, char *secstrings)
+{
+        unsigned int i;
+
+        /* only scan the sections containing data */
+        kmemleak_scan_area(mod->module_core, (unsigned long)mod -
+                           (unsigned long)mod->module_core,
+                           sizeof(struct module), GFP_KERNEL);
+
+        for (i = 1; i < hdr->e_shnum; i++) {
+                if (!(sechdrs[i].sh_flags & SHF_ALLOC))
+                        continue;
+                if (strncmp(secstrings + sechdrs[i].sh_name, ".data", 5) != 0
+                    && strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) != 0)
+                        continue;
+
+                kmemleak_scan_area(mod->module_core, sechdrs[i].sh_addr -
+                                   (unsigned long)mod->module_core,
+                                   sechdrs[i].sh_size, GFP_KERNEL);
+        }
+}
+#else
+static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
+                                        Elf_Shdr *sechdrs, char *secstrings)
+{
+}
+#endif
+
 /* Allocate and load the module: note that size of section 0 is always
    zero, and we rely on this for optional sections. */
 static noinline struct module *load_module(void __user *umod,
@@ -2046,6 +2088,12 @@ static noinline struct module *load_module(void __user *umod,
 
         /* Do the allocs. */
         ptr = module_alloc_update_bounds(mod->core_size);
+        /*
+         * The pointer to this block is stored in the module structure
+         * which is inside the block. Just mark it as not being a
+         * leak.
+         */
+        kmemleak_not_leak(ptr);
         if (!ptr) {
                 err = -ENOMEM;
                 goto free_percpu;
@@ -2054,6 +2102,13 @@ static noinline struct module *load_module(void __user *umod,
         mod->module_core = ptr;
 
         ptr = module_alloc_update_bounds(mod->init_size);
+        /*
+         * The pointer to this block is stored in the module structure
+         * which is inside the block. This block doesn't need to be
+         * scanned as it contains data and code that will be freed
+         * after the module is initialized.
+         */
+        kmemleak_ignore(ptr);
         if (!ptr && mod->init_size) {
                 err = -ENOMEM;
                 goto free_core;
@@ -2084,6 +2139,7 @@ static noinline struct module *load_module(void __user *umod,
         }
         /* Module has been moved. */
         mod = (void *)sechdrs[modindex].sh_addr;
+        kmemleak_load_module(mod, hdr, sechdrs, secstrings);
 
 #if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP)
         mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t),