arm64 KASAN_HW_TAGS panic on non-MTE hardware on 5.12-rc1
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2021-03-05 17:13:11
Hi Andrey, Enabling CONFIG_KASAN_HW_TAGS and running the resulting kernel on non-MTE hardware panics with an undefined STG instruction from mte_set_mem_tag_range(): ./scripts/faddr2line vmlinux kasan_unpoison_task_stack+0x18/0x40 kasan_unpoison_task_stack+0x18/0x40: mte_set_mem_tag_range at arch/arm64/include/asm/mte-kasan.h:71 (inlined by) mte_set_mem_tag_range at arch/arm64/include/asm/mte-kasan.h:56 (inlined by) kasan_unpoison at mm/kasan/kasan.h:363 (inlined by) kasan_unpoison_task_stack at mm/kasan/common.c:72 The full trace: ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/traps.c:406! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.12.0-rc1-00002-ge76afd1d69f3-dirty #2 pstate: 00000085 (nzcv daIf -PAN -UAO -TCO BTYPE=--) pc : do_undefinstr+0x2c8/0x2e8 lr : do_undefinstr+0x2d4/0x2e8 sp : ffffc07baeaa3cf0 x29: ffffc07baeaa3cf0 x28: ffffc07baeab3280 x27: ffffc07baeaa9a00 x26: ffffc07baeaa7000 x25: ffffc07baeab3964 x24: ffffc07baeaa9c00 x23: 0000000040000085 x22: ffffc07baed7f0e0 x21: 00000000d9200800 x20: ffffc07baeab3280 x19: ffffc07baeaa3d80 x18: 0000000000000200 x17: 000000000000000b x16: 0000000000007fff x15: 00000000ffffffff x14: 0000000000000000 x13: 0000000000000048 x12: ffffc07baeab3280 x11: ffff64d0ffc00294 x10: 0000000000000000 x9 : 0000000000000000 x8 : 00000000389fd980 x7 : ffff64d0ffbde5b8 x6 : 0000000000000000 x5 : ffff64d0ffb99880 x4 : ffffc07baeab5710 x3 : ffffc07baed7f0f0 x2 : 0000000000000000 x1 : ffffc07baeab3280 x0 : 0000000040000085 Call trace: do_undefinstr+0x2c8/0x2e8 el1_undef+0x30/0x50 el1_sync_handler+0x8c/0xc8 el1_sync+0x70/0x100 kasan_unpoison_task_stack+0x18/0x40 sched_init+0x390/0x3f0 start_kernel+0x2cc/0x540 0x0 Code: 17ffff8a f9401bf7 17ffffc8 f9001bf7 (d4210000) random: get_random_bytes called from print_oops_end_marker+0x2c/0x68 with crng_init=0 ---[ end trace c881f708bdfe36c8 ]--- If MTE is not available, I thought we should not end up calling the MTE backend but it seems that kasan expects the backend to skip the undefined instructions. Does kasan fall back to sw_tags if hw_tags are not available or it just disables kasan altogether? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel