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    Subject[PATCH 5.16 0503/1039] efi: apply memblock cap after memblock_add()
    Date
    From: Pingfan Liu <kernelfans@gmail.com>

    [ Upstream commit b398123bff3bcbc1facb0f29bf6e7b9f1bc55931 ]

    On arm64, during kdump kernel saves vmcore, it runs into the following bug:
    ...
    [ 15.148919] usercopy: Kernel memory exposure attempt detected from SLUB object 'kmem_cache_node' (offset 0, size 4096)!
    [ 15.159707] ------------[ cut here ]------------
    [ 15.164311] kernel BUG at mm/usercopy.c:99!
    [ 15.168482] Internal error: Oops - BUG: 0 [#1] SMP
    [ 15.173261] Modules linked in: xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce sbsa_gwdt ast i2c_algo_bit drm_vram_helper drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec drm_ttm_helper ttm drm nvme nvme_core xgene_hwmon i2c_designware_platform i2c_designware_core dm_mirror dm_region_hash dm_log dm_mod overlay squashfs zstd_decompress loop
    [ 15.206186] CPU: 0 PID: 542 Comm: cp Not tainted 5.16.0-rc4 #1
    [ 15.212006] Hardware name: GIGABYTE R272-P30-JG/MP32-AR0-JG, BIOS F12 (SCP: 1.5.20210426) 05/13/2021
    [ 15.221125] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    [ 15.228073] pc : usercopy_abort+0x9c/0xa0
    [ 15.232074] lr : usercopy_abort+0x9c/0xa0
    [ 15.236070] sp : ffff8000121abba0
    [ 15.239371] x29: ffff8000121abbb0 x28: 0000000000003000 x27: 0000000000000000
    [ 15.246494] x26: 0000000080000400 x25: 0000ffff885c7000 x24: 0000000000000000
    [ 15.253617] x23: 000007ff80400000 x22: ffff07ff80401000 x21: 0000000000000001
    [ 15.260739] x20: 0000000000001000 x19: ffff07ff80400000 x18: ffffffffffffffff
    [ 15.267861] x17: 656a626f2042554c x16: 53206d6f72662064 x15: 6574636574656420
    [ 15.274983] x14: 74706d6574746120 x13: 2129363930342065 x12: 7a6973202c302074
    [ 15.282105] x11: ffffc8b041d1b148 x10: 00000000ffff8000 x9 : ffffc8b04012812c
    [ 15.289228] x8 : 00000000ffff7fff x7 : ffffc8b041d1b148 x6 : 0000000000000000
    [ 15.296349] x5 : 0000000000000000 x4 : 0000000000007fff x3 : 0000000000000000
    [ 15.303471] x2 : 0000000000000000 x1 : ffff07ff8c064800 x0 : 000000000000006b
    [ 15.310593] Call trace:
    [ 15.313027] usercopy_abort+0x9c/0xa0
    [ 15.316677] __check_heap_object+0xd4/0xf0
    [ 15.320762] __check_object_size.part.0+0x160/0x1e0
    [ 15.325628] __check_object_size+0x2c/0x40
    [ 15.329711] copy_oldmem_page+0x7c/0x140
    [ 15.333623] read_from_oldmem.part.0+0xfc/0x1c0
    [ 15.338142] __read_vmcore.constprop.0+0x23c/0x350
    [ 15.342920] read_vmcore+0x28/0x34
    [ 15.346309] proc_reg_read+0xb4/0xf0
    [ 15.349871] vfs_read+0xb8/0x1f0
    [ 15.353088] ksys_read+0x74/0x100
    [ 15.356390] __arm64_sys_read+0x28/0x34
    ...

    This bug introduced by commit b261dba2fdb2 ("arm64: kdump: Remove custom
    linux,usable-memory-range handling"), which moves
    memblock_cap_memory_range() to fdt, but it breaches the rules that
    memblock_cap_memory_range() should come after memblock_add() etc as said
    in commit e888fa7bb882 ("memblock: Check memory add/cap ordering").

    As a consequence, the virtual address set up by copy_oldmem_page() does
    not bail out from the test of virt_addr_valid() in check_heap_object(),
    and finally hits the BUG_ON().

    Since memblock allocator has no idea about when the memblock is fully
    populated, while efi_init() is aware, so tackling this issue by calling the
    interface early_init_dt_check_for_usable_mem_range() exposed by of/fdt.

    Fixes: b261dba2fdb2 ("arm64: kdump: Remove custom linux,usable-memory-range handling")
    Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
    Cc: Rob Herring <robh+dt@kernel.org>
    Cc: Zhen Lei <thunder.leizhen@huawei.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will@kernel.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Mike Rapoport <rppt@kernel.org>
    Cc: Geert Uytterhoeven <geert+renesas@glider.be>
    Cc: Frank Rowand <frowand.list@gmail.com>
    Cc: Ard Biesheuvel <ardb@kernel.org>
    Cc: Nick Terrell <terrelln@fb.com>
    Cc: linux-arm-kernel@lists.infradead.org
    To: devicetree@vger.kernel.org
    To: linux-efi@vger.kernel.org
    Acked-by: Ard Biesheuvel <ardb@kernel.org>
    Signed-off-by: Rob Herring <robh@kernel.org>
    Link: https://lore.kernel.org/r/20211215021348.8766-1-kernelfans@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/firmware/efi/efi-init.c | 5 +++++
    drivers/of/fdt.c | 2 +-
    include/linux/of_fdt.h | 2 ++
    3 files changed, 8 insertions(+), 1 deletion(-)

    diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c
    index b19ce1a83f91a..b2c829e95bd14 100644
    --- a/drivers/firmware/efi/efi-init.c
    +++ b/drivers/firmware/efi/efi-init.c
    @@ -235,6 +235,11 @@ void __init efi_init(void)
    }

    reserve_regions();
    + /*
    + * For memblock manipulation, the cap should come after the memblock_add().
    + * And now, memblock is fully populated, it is time to do capping.
    + */
    + early_init_dt_check_for_usable_mem_range();
    efi_esrt_init();
    efi_mokvar_table_init();

    diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
    index 5a238a933eb29..65af475dfa950 100644
    --- a/drivers/of/fdt.c
    +++ b/drivers/of/fdt.c
    @@ -971,7 +971,7 @@ static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND;
    * early_init_dt_check_for_usable_mem_range - Decode usable memory range
    * location from flat tree
    */
    -static void __init early_init_dt_check_for_usable_mem_range(void)
    +void __init early_init_dt_check_for_usable_mem_range(void)
    {
    const __be32 *prop;
    int len;
    diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
    index cf48983d3c867..ad09beb6d13c4 100644
    --- a/include/linux/of_fdt.h
    +++ b/include/linux/of_fdt.h
    @@ -62,6 +62,7 @@ extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
    int depth, void *data);
    extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
    int depth, void *data);
    +extern void early_init_dt_check_for_usable_mem_range(void);
    extern int early_init_dt_scan_chosen_stdout(void);
    extern void early_init_fdt_scan_reserved_mem(void);
    extern void early_init_fdt_reserve_self(void);
    @@ -86,6 +87,7 @@ extern void unflatten_and_copy_device_tree(void);
    extern void early_init_devtree(void *);
    extern void early_get_first_memblock_info(void *, phys_addr_t *);
    #else /* CONFIG_OF_EARLY_FLATTREE */
    +static inline void early_init_dt_check_for_usable_mem_range(void) {}
    static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }
    static inline void early_init_fdt_scan_reserved_mem(void) {}
    static inline void early_init_fdt_reserve_self(void) {}
    --
    2.34.1


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