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    Subject[PATCH 7/8] lkdtm: crash on overwriting protected pmalloc var
    Date
    Verify that pmalloc read-only protection is in place: trying to
    overwrite a protected variable will crash the kernel.

    Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com>
    ---
    drivers/misc/lkdtm.h | 1 +
    drivers/misc/lkdtm_core.c | 3 +++
    drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++
    3 files changed, 32 insertions(+)

    diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
    index 9e513dcfd809..dcda3ae76ceb 100644
    --- a/drivers/misc/lkdtm.h
    +++ b/drivers/misc/lkdtm.h
    @@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
    void __init lkdtm_perms_init(void);
    void lkdtm_WRITE_RO(void);
    void lkdtm_WRITE_RO_AFTER_INIT(void);
    +void lkdtm_WRITE_RO_PMALLOC(void);
    void lkdtm_WRITE_KERN(void);
    void lkdtm_EXEC_DATA(void);
    void lkdtm_EXEC_STACK(void);
    diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
    index 2154d1bfd18b..c9fd42bda6ee 100644
    --- a/drivers/misc/lkdtm_core.c
    +++ b/drivers/misc/lkdtm_core.c
    @@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = {
    CRASHTYPE(ACCESS_USERSPACE),
    CRASHTYPE(WRITE_RO),
    CRASHTYPE(WRITE_RO_AFTER_INIT),
    +#ifdef CONFIG_PROTECTABLE_MEMORY
    + CRASHTYPE(WRITE_RO_PMALLOC),
    +#endif
    CRASHTYPE(WRITE_KERN),
    CRASHTYPE(REFCOUNT_INC_OVERFLOW),
    CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
    diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c
    index 53b85c9d16b8..0ac9023fd2b0 100644
    --- a/drivers/misc/lkdtm_perms.c
    +++ b/drivers/misc/lkdtm_perms.c
    @@ -9,6 +9,7 @@
    #include <linux/vmalloc.h>
    #include <linux/mman.h>
    #include <linux/uaccess.h>
    +#include <linux/pmalloc.h>
    #include <asm/cacheflush.h>

    /* Whether or not to fill the target memory area with do_nothing(). */
    @@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void)
    *ptr ^= 0xabcd1234;
    }

    +#ifdef CONFIG_PROTECTABLE_MEMORY
    +void lkdtm_WRITE_RO_PMALLOC(void)
    +{
    + struct gen_pool *pool;
    + int *i;
    +
    + pool = pmalloc_create_pool("pool", 0);
    + if (unlikely(!pool)) {
    + pr_info("Failed preparing pool for pmalloc test.");
    + return;
    + }
    +
    + i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
    + if (unlikely(!i)) {
    + pr_info("Failed allocating memory for pmalloc test.");
    + pmalloc_destroy_pool(pool);
    + return;
    + }
    +
    + *i = INT_MAX;
    + pmalloc_protect_pool(pool);
    +
    + pr_info("attempting bad pmalloc write at %p\n", i);
    + *i = 0;
    +}
    +#endif
    +
    void lkdtm_WRITE_KERN(void)
    {
    size_t size;
    --
    2.14.1
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