From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: [PATCH 1/1] efi/arm64: add a terminator for ptdump marker Date: Sat, 2 Feb 2019 10:50:17 +0100 Message-ID: <20190202095017.13799-2-ard.biesheuvel@linaro.org> References: <20190202095017.13799-1-ard.biesheuvel@linaro.org> Return-path: In-Reply-To: <20190202095017.13799-1-ard.biesheuvel@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-efi@vger.kernel.org, Ingo Molnar , Thomas Gleixner Cc: Ard Biesheuvel , linux-kernel@vger.kernel.org, Qian Cai List-Id: linux-efi@vger.kernel.org From: Qian Cai Reading efi_page_tables debugfs triggers an out-of-bounds access here, arch/arm64/mm/dump.c: 282 if (addr >= st->marker[1].start_address) { called from, arch/arm64/mm/dump.c: 331 note_page(st, addr, 2, pud_val(pud)); because st->marker++ is is called after "UEFI runtime end" which is the last element in addr_marker[]. Therefore, add a terminator like the one for kernel_page_tables, so it can be skipped to print out non-existent markers. # cat /sys/kernel/debug/efi_page_tables ---[ UEFI runtime start ]--- 0x0000000020000000-0x0000000020010000 64K PTE RW NX SHD AF ... 0x0000000020200000-0x0000000021340000 17664K PTE RW NX SHD AF ... ... 0x0000000021920000-0x0000000021950000 192K PTE RW x SHD AF ... 0x0000000021950000-0x00000000219a0000 320K PTE RW NX SHD AF ... ---[ UEFI runtime end ]--- ---[ (null) ]--- ---[ (null) ]--- [12126.163970] BUG: KASAN: global-out-of-bounds in note_page+0x1f0/0xac0 [12126.170404] Read of size 8 at addr ffff2000123f2ac0 by task read_all/42464 [12126.199520] Call trace: [12126.201972] dump_backtrace+0x0/0x298 [12126.205627] show_stack+0x24/0x30 [12126.208944] dump_stack+0xb0/0xdc [12126.212258] print_address_description+0x64/0x2b0 [12126.216954] kasan_report+0x150/0x1a4 [12126.220610] __asan_report_load8_noabort+0x30/0x3c [12126.225392] note_page+0x1f0/0xac0 [12126.228786] walk_pgd+0xb4/0x244 [12126.232005] ptdump_walk_pgd+0xec/0x140 [12126.235833] ptdump_show+0x40/0x50 [12126.239237] seq_read+0x3f8/0xad0 [12126.242548] full_proxy_read+0x9c/0xc0 [12126.246290] __vfs_read+0xfc/0x4c8 [12126.249684] vfs_read+0xec/0x208 [12126.252904] ksys_read+0xd0/0x15c [12126.256210] __arm64_sys_read+0x84/0x94 [12126.260048] el0_svc_handler+0x258/0x304 [12126.263963] el0_svc+0x8/0xc [12126.266834] [12126.268317] The buggy address belongs to the variable: [12126.273458] __compound_literal.0+0x20/0x800 [12126.277718] [12126.279201] Memory state around the buggy address: [12126.283987] ffff2000123f2980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [12126.291200] ffff2000123f2a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fa [12126.298412] >ffff2000123f2a80: fa fa fa fa 00 00 00 00 fa fa fa fa 00 00 00 00 [12126.305624] ^ [12126.310927] ffff2000123f2b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [12126.318140] ffff2000123f2b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0 Fixes: 9d80448ac92b ("efi/arm64: Add debugfs node to dump UEFI runtime page tables") Signed-off-by: Qian Cai [ardb: fix up whitespace] Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/arm-runtime.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c index 23ea1ed409d1..352bd2473162 100644 --- a/drivers/firmware/efi/arm-runtime.c +++ b/drivers/firmware/efi/arm-runtime.c @@ -37,8 +37,9 @@ extern u64 efi_system_table; static struct ptdump_info efi_ptdump_info = { .mm = &efi_mm, .markers = (struct addr_marker[]){ - { 0, "UEFI runtime start" }, - { DEFAULT_MAP_WINDOW_64, "UEFI runtime end" } + { 0, "UEFI runtime start" }, + { DEFAULT_MAP_WINDOW_64, "UEFI runtime end" }, + { -1, NULL } }, .base_addr = 0, }; -- 2.17.1