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    Subject[PATCH 6.0 791/862] ARM: 9242/1: kasan: Only map modules if CONFIG_KASAN_VMALLOC=n
    Date
    From: Alex Sverdlin <alexander.sverdlin@nokia.com>

    [ Upstream commit 823f606ab6b4759a1faf0388abcf4fb0776710d2 ]

    In case CONFIG_KASAN_VMALLOC=y kasan_populate_vmalloc() allocates the
    shadow pages dynamically. But even worse is that kasan_release_vmalloc()
    releases them, which is not compatible with create_mapping() of
    MODULES_VADDR..MODULES_END range:

    BUG: Bad page state in process kworker/9:1 pfn:2068b
    page:e5e06160 refcount:0 mapcount:0 mapping:00000000 index:0x0
    flags: 0x1000(reserved)
    raw: 00001000 e5e06164 e5e06164 00000000 00000000 00000000 ffffffff 00000000
    page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
    bad because of flags: 0x1000(reserved)
    Modules linked in: ip_tables
    CPU: 9 PID: 154 Comm: kworker/9:1 Not tainted 5.4.188-... #1
    Hardware name: LSI Axxia AXM55XX
    Workqueue: events do_free_init
    unwind_backtrace
    show_stack
    dump_stack
    bad_page
    free_pcp_prepare
    free_unref_page
    kasan_depopulate_vmalloc_pte
    __apply_to_page_range
    apply_to_existing_page_range
    kasan_release_vmalloc
    __purge_vmap_area_lazy
    _vm_unmap_aliases.part.0
    __vunmap
    do_free_init
    process_one_work
    worker_thread
    kthread

    Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
    Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm/mm/kasan_init.c | 9 +++++++--
    1 file changed, 7 insertions(+), 2 deletions(-)

    diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
    index 29caee9c79ce..46d9f4a622cb 100644
    --- a/arch/arm/mm/kasan_init.c
    +++ b/arch/arm/mm/kasan_init.c
    @@ -268,12 +268,17 @@ void __init kasan_init(void)

    /*
    * 1. The module global variables are in MODULES_VADDR ~ MODULES_END,
    - * so we need to map this area.
    + * so we need to map this area if CONFIG_KASAN_VMALLOC=n. With
    + * VMALLOC support KASAN will manage this region dynamically,
    + * refer to kasan_populate_vmalloc() and ARM's implementation of
    + * module_alloc().
    * 2. PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR
    * ~ MODULES_END's shadow is in the same PMD_SIZE, so we can't
    * use kasan_populate_zero_shadow.
    */
    - create_mapping((void *)MODULES_VADDR, (void *)(PKMAP_BASE + PMD_SIZE));
    + if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) && IS_ENABLED(CONFIG_MODULES))
    + create_mapping((void *)MODULES_VADDR, (void *)(MODULES_END));
    + create_mapping((void *)PKMAP_BASE, (void *)(PKMAP_BASE + PMD_SIZE));

    /*
    * KAsan may reuse the contents of kasan_early_shadow_pte directly, so
    --
    2.35.1


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