[PATCH 5.16 0503/1039] efi: apply memblock cap after memblock_add()

From: Greg Kroah-Hartman
Date: Mon Jan 24 2022 - 17:04:59 EST

From: Pingfan Liu <kernelfans@xxxxxxxxx>

[ 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@xxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Cc: Frank Rowand <frowand.list@xxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Nick Terrell <terrelln@xxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
To: devicetree@xxxxxxxxxxxxxxx
To: linux-efi@xxxxxxxxxxxxxxx
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211215021348.8766-1-kernelfans@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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