With the introduction of KASAN_HW_TAGS, kasan_report() currently assumes that every location in memory has valid metadata associated. This is due to the fact that addr_has_metadata() returns always true.
As a consequence of this, an invalid address (e.g. NULL pointer address) passed to kasan_report() when KASAN_HW_TAGS is enabled, leads to a kernel panic. Example below, based on arm64: ================================================================== BUG: KASAN: invalid-access in 0x0 Read at addr 0000000000000000 by task swapper/0/1 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Mem abort info: ESR = 0x96000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 ... Call trace: mte_get_mem_tag+0x24/0x40 kasan_report+0x1a4/0x410 alsa_sound_last_init+0x8c/0xa4 do_one_initcall+0x50/0x1b0 kernel_init_freeable+0x1d4/0x23c kernel_init+0x14/0x118 ret_from_fork+0x10/0x34 Code: d65f03c0 9000f021 f9428021 b6cfff61 (d9600000) ---[ end trace 377c8bb45bdd3a1a ]--- hrtimer: interrupt took 48694256 ns note: swapper/0[1] exited with preempt_count 1 Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b SMP: stopping secondary CPUs Kernel Offset: 0x35abaf140000 from 0xffff800010000000 PHYS_OFFSET: 0x40000000 CPU features: 0x0a7e0152,61c0a030 Memory Limit: none ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- This series fixes the behavior of addr_has_metadata() that now returns true only when the address is valid. Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> Cc: Alexander Potapenko <gli...@google.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Leon Romanovsky <leo...@mellanox.com> Cc: Andrey Konovalov <andreyk...@google.com> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <w...@kernel.org> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Paul E. McKenney <paul...@kernel.org> Cc: Naresh Kamboju <naresh.kamb...@linaro.org> Signed-off-by: Vincenzo Frascino <vincenzo.frasc...@arm.com> Vincenzo Frascino (2): kasan: Add explicit preconditions to kasan_report() kasan: Make addr_has_metadata() return true for valid addresses include/linux/kasan.h | 7 +++++++ mm/kasan/kasan.h | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-) -- 2.30.0
