From: Vincenzo Frascino vincenzo.frascino@arm.com
[ Upstream commit 49c6631d3b4f61a7b5bb0453a885a12bfa06ffd8 ]
Patch series "kasan: Fix metadata detection for KASAN_HW_TAGS", v5.
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.
This patch (of 2):
With the introduction of KASAN_HW_TAGS, kasan_report() accesses the metadata only when addr_has_metadata() succeeds.
Add a comment to make sure that the preconditions to the function are explicitly clarified.
Link: https://lkml.kernel.org/r/20210126134409.47894-1-vincenzo.frascino@arm.com Link: https://lkml.kernel.org/r/20210126134409.47894-2-vincenzo.frascino@arm.com Signed-off-by: Vincenzo Frascino vincenzo.frascino@arm.com Reviewed-by: Andrey Konovalov andreyknvl@google.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Leon Romanovsky leonro@mellanox.com Cc: Andrey Konovalov andreyknvl@google.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: "Paul E . McKenney" paulmck@kernel.org Cc: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/kasan.h | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 30d343b4a40a5..646fa165d2cce 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -196,6 +196,13 @@ void kasan_init_tags(void);
void *kasan_reset_tag(const void *addr);
+/** + * kasan_report - print a report about a bad memory access detected by KASAN + * @addr: address of the bad access + * @size: size of the bad access + * @is_write: whether the bad access is a write or a read + * @ip: instruction pointer for the accessibility check or the bad access itself + */ bool kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip);