evie/android_kernel_oneplus_msm8998
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FROMLIST: arm64: Handle faults caused by inadvertent user access with PAN enabled

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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 <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Change-Id: I623113fc8bf6d5f023aeec7a0640b62a25ef8420
(cherry picked from commit be3db9340c8011d22f06715339b66bcbbd4893bd)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Catalin Marinas 2016-07-01 18:22:39 +01:00 • committed by Sami Tolvanen
parent 5775ca3482
commit 5dc2b7c7bb
1 changed files with 14 additions and 8 deletions
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22
arch/arm64/mm/fault.c
View file

@ -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)) {
/* regs->orig_addr_limit may be 0 if we entered from EL0 */
if (regs->orig_addr_limit == KERNEL_DS)
die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
@ -478,10 +484,10 @@ 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" },