The patch titled
Subject: kasan: add explicit preconditions to kasan_report()
has been added to the -mm tree. Its filename is
kasan-add-explicit-preconditions-to-kasan_report.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-add-explicit-preconditions-to-kasan_report.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-add-explicit-preconditions-to-kasan_report.patch
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------------------------------------------------------
From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Subject: kasan: add explicit preconditions to kasan_report()
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@xxxxxxx
Link: https://lkml.kernel.org/r/20210126134409.47894-2-vincenzo.frascino@xxxxxxx
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: "Paul E . McKenney" <paulmck@xxxxxxxxxx>
Cc: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kasan.h | 7 +++++++
1 file changed, 7 insertions(+)
--- a/include/linux/kasan.h~kasan-add-explicit-preconditions-to-kasan_report
+++ a/include/linux/kasan.h
@@ -333,6 +333,13 @@ static inline void *kasan_reset_tag(cons
return (void *)arch_kasan_reset_tag(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);
_
Patches currently in -mm which might be from vincenzo.frascino@xxxxxxx are
kasan-add-explicit-preconditions-to-kasan_report.patch
kasan-make-addr_has_metadata-return-true-for-valid-addresses.patch
