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authorCatalin Marinas <catalin.marinas@arm.com>2016-03-10 21:41:16 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2016-03-11 14:03:35 +0300
commit2776e0e8ef683a42fe3e9a5facf576b73579700e (patch)
tree79bdb7198b58df22cd6bfd4727d0357195098e76
parent2f76969f2eef051bdd63d38b08d78e790440b0ad (diff)
downloadlinux-2776e0e8ef683a42fe3e9a5facf576b73579700e.tar.xz
arm64: kasan: Fix zero shadow mapping overriding kernel image shadow
With the 16KB and 64KB page size configurations, SWAPPER_BLOCK_SIZE is PAGE_SIZE and ARM64_SWAPPER_USES_SECTION_MAPS is 0. Since kimg_shadow_end is not page aligned (_end shifted by KASAN_SHADOW_SCALE_SHIFT), the edges of previously mapped kernel image shadow via vmemmap_populate() may be overridden by subsequent calls to kasan_populate_zero_shadow(), leading to kernel panics like below: ------------------------------------------------------------------------------ Unable to handle kernel paging request at virtual address fffffc100135068c pgd = fffffc8009ac0000 [fffffc100135068c] *pgd=00000009ffee0003, *pud=00000009ffee0003, *pmd=00000009ffee0003, *pte=00e0000081a00793 Internal error: Oops: 9600004f [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc4+ #1984 Hardware name: Juno (DT) task: fffffe09001a0000 ti: fffffe0900200000 task.ti: fffffe0900200000 PC is at __memset+0x4c/0x200 LR is at kasan_unpoison_shadow+0x34/0x50 pc : [<fffffc800846f1cc>] lr : [<fffffc800821ff54>] pstate: 00000245 sp : fffffe0900203db0 x29: fffffe0900203db0 x28: 0000000000000000 x27: 0000000000000000 x26: 0000000000000000 x25: fffffc80099b69d0 x24: 0000000000000001 x23: 0000000000000000 x22: 0000000000002000 x21: dffffc8000000000 x20: 1fffff9001350a8c x19: 0000000000002000 x18: 0000000000000008 x17: 0000000000000147 x16: ffffffffffffffff x15: 79746972100e041d x14: ffffff0000000000 x13: ffff000000000000 x12: 0000000000000000 x11: 0101010101010101 x10: 1fffffc11c000000 x9 : 0000000000000000 x8 : fffffc100135068c x7 : 0000000000000000 x6 : 000000000000003f x5 : 0000000000000040 x4 : 0000000000000004 x3 : fffffc100134f651 x2 : 0000000000000400 x1 : 0000000000000000 x0 : fffffc100135068c Process swapper/0 (pid: 1, stack limit = 0xfffffe0900200020) Call trace: [<fffffc800846f1cc>] __memset+0x4c/0x200 [<fffffc8008220044>] __asan_register_globals+0x5c/0xb0 [<fffffc8008a09d34>] _GLOBAL__sub_I_65535_1_sunrpc_cache_lookup+0x1c/0x28 [<fffffc8008f20d28>] kernel_init_freeable+0x104/0x274 [<fffffc80089e1948>] kernel_init+0x10/0xf8 [<fffffc8008093a00>] ret_from_fork+0x10/0x50 ------------------------------------------------------------------------------ This patch aligns kimg_shadow_start and kimg_shadow_end to SWAPPER_BLOCK_SIZE in all configurations. Fixes: f9040773b7bb ("arm64: move kernel image to base of vmalloc area") Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
-rw-r--r--arch/arm64/mm/kasan_init.c13
1 files changed, 5 insertions, 8 deletions
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index a164183f3481..757009daa9ed 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -159,15 +159,12 @@ void __init kasan_init(void)
* vmemmap_populate() has populated the shadow region that covers the
* kernel image with SWAPPER_BLOCK_SIZE mappings, so we have to round
* the start and end addresses to SWAPPER_BLOCK_SIZE as well, to prevent
- * kasan_populate_zero_shadow() from replacing the PMD block mappings
- * with PMD table mappings at the edges of the shadow region for the
- * kernel image.
+ * kasan_populate_zero_shadow() from replacing the page table entries
+ * (PMD or PTE) at the edges of the shadow region for the kernel
+ * image.
*/
- if (ARM64_SWAPPER_USES_SECTION_MAPS) {
- kimg_shadow_start = round_down(kimg_shadow_start,
- SWAPPER_BLOCK_SIZE);
- kimg_shadow_end = round_up(kimg_shadow_end, SWAPPER_BLOCK_SIZE);
- }
+ kimg_shadow_start = round_down(kimg_shadow_start, SWAPPER_BLOCK_SIZE);
+ kimg_shadow_end = round_up(kimg_shadow_end, SWAPPER_BLOCK_SIZE);
kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
(void *)mod_shadow_start);