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    Subject[PATCH 08/14] kmemleak: Add modules support
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    Date
    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>
    ---
    kernel/module.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 56 insertions(+), 0 deletions(-)

    diff --git a/kernel/module.c b/kernel/module.c
    index e797812..81b32f9 100644
    --- a/kernel/module.c
    +++ b/kernel/module.c
    @@ -52,6 +52,7 @@
    #include <linux/ftrace.h>
    #include <linux/async.h>
    #include <linux/percpu.h>
    +#include <linux/kmemleak.h>

    #if 0
    #define DEBUGP printk
    @@ -429,6 +430,7 @@ 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",
    @@ -458,6 +460,11 @@ 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;
    @@ -472,6 +479,7 @@ 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++) {
    @@ -483,6 +491,10 @@ 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];
    @@ -1878,6 +1890,36 @@ 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,
    @@ -2050,6 +2092,12 @@ 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;
    @@ -2058,6 +2106,13 @@ 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;
    @@ -2088,6 +2143,7 @@ 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),


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