On Tue, Nov 10, 2020 at 11:12 PM 'Andrey Konovalov' via kasan-dev
<kasan-dev@xxxxxxxxxxxxxxxx> wrote:
>
> Add error reporting for hardware tag-based KASAN. When CONFIG_KASAN_HW_TAGS
> is enabled, print KASAN report from the arm64 tag fault handler.
>
> SAS bits aren't set in ESR for all faults reported in EL1, so it's
> impossible to find out the size of the access the caused the fault.
> Adapt KASAN reporting code to handle this case.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Co-developed-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---
> Change-Id: I3780fe7db6e075dff2937d3d8508f55c9322b095
> ---
> arch/arm64/mm/fault.c | 14 ++++++++++++++
> mm/kasan/report.c | 11 ++++++++---
> 2 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index fbceb14d93b1..7370e822e588 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -14,6 +14,7 @@
> #include <linux/mm.h>
> #include <linux/hardirq.h>
> #include <linux/init.h>
> +#include <linux/kasan.h>
> #include <linux/kprobes.h>
> #include <linux/uaccess.h>
> #include <linux/page-flags.h>
> @@ -297,10 +298,23 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
> do_exit(SIGKILL);
> }
>
> +#ifdef CONFIG_KASAN_HW_TAGS
> static void report_tag_fault(unsigned long addr, unsigned int esr,
> struct pt_regs *regs)
> {
> + bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
> +
> + /*
> + * SAS bits aren't set for all faults reported in EL1, so we can't
> + * find out access size.
> + */
> + kasan_report(addr, 0, is_write, regs->pc);
> }
> +#else
> +/* Tag faults aren't enabled without CONFIG_KASAN_HW_TAGS. */
> +static inline void report_tag_fault(unsigned long addr, unsigned int esr,
> + struct pt_regs *regs) { }
> +#endif
>
> static void do_tag_recovery(unsigned long addr, unsigned int esr,
> struct pt_regs *regs)
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 8afc1a6ab202..ce06005d4052 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -62,9 +62,14 @@ static void print_error_description(struct kasan_access_info *info)
> {
> pr_err("BUG: KASAN: %s in %pS\n",
> get_bug_type(info), (void *)info->ip);
> - pr_err("%s of size %zu at addr %px by task %s/%d\n",
> - info->is_write ? "Write" : "Read", info->access_size,
> - info->access_addr, current->comm, task_pid_nr(current));
> + if (info->access_size)
> + pr_err("%s of size %zu at addr %px by task %s/%d\n",
> + info->is_write ? "Write" : "Read", info->access_size,
> + info->access_addr, current->comm, task_pid_nr(current));
> + else
> + pr_err("%s at addr %px by task %s/%d\n",
> + info->is_write ? "Write" : "Read",
> + info->access_addr, current->comm, task_pid_nr(current));
> }
>
> static DEFINE_SPINLOCK(report_lock);
> --
> 2.29.2.222.g5d2a92d10f8-goog
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@xxxxxxxxxxxxxxxx.
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/fe78d723ba64456d68754a944fa93fe4a25c730f.1605046192.git.andreyknvl%40google.com.
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
