From 0a75f2be2d16a271d64b20f9dc7de3e2629652a1 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 1 Jul 2016 18:22:39 +0100 Subject: [PATCH] FROMLIST: arm64: Handle faults caused by inadvertent user access with PAN enabled When TTBR0_EL1 is set to the reserved page, an erroneous kernel access to user space would generate a translation fault. This patch adds the checks for the software-set PSR_PAN_BIT to emulate a permission fault and report it accordingly. This patch also updates the description of the synchronous external aborts on translation table walks. Cc: Will Deacon Cc: James Morse Cc: Kees Cook Cc: Mark Rutland Signed-off-by: Catalin Marinas Change-Id: I623113fc8bf6d5f023aeec7a0640b62a25ef8420 (cherry picked from commit be3db9340c8011d22f06715339b66bcbbd4893bd) Signed-off-by: Sami Tolvanen [Conflict fixes in lsk-v4.4-android topic branch] Signed-off-by: Amit Pundir --- arch/arm64/mm/fault.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index dcac3ad04d84..94dd6c02fd49 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -246,13 +246,19 @@ out: return fault; } -static inline bool is_permission_fault(unsigned int esr) +static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs) { unsigned int ec = ESR_ELx_EC(esr); unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE; - return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM) || - (ec == ESR_ELx_EC_IABT_CUR && fsc_type == ESR_ELx_FSC_PERM); + if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR) + return false; + + if (system_uses_ttbr0_pan()) + return fsc_type == ESR_ELx_FSC_FAULT && + (regs->pstate & PSR_PAN_BIT); + else + return fsc_type == ESR_ELx_FSC_PERM; } static bool is_el0_instruction_abort(unsigned int esr) @@ -293,7 +299,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, mm_flags |= FAULT_FLAG_WRITE; } - if (is_permission_fault(esr) && (addr < USER_DS)) { + if (addr < USER_DS && is_permission_fault(esr, regs)) { if (get_fs() == KERNEL_DS) die("Accessing user space memory with fs=KERNEL_DS", regs, esr); @@ -477,10 +483,10 @@ static const struct fault_info { { do_bad, SIGBUS, 0, "unknown 17" }, { do_bad, SIGBUS, 0, "unknown 18" }, { do_bad, SIGBUS, 0, "unknown 19" }, - { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, - { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, - { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, - { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, + { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, + { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, + { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, + { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, { do_bad, SIGBUS, 0, "synchronous parity error" }, { do_bad, SIGBUS, 0, "unknown 25" }, { do_bad, SIGBUS, 0, "unknown 26" }, -- 2.34.1