The patch titled
Subject: kasan: fix Oops due to missing calls to kasan_arch_is_ready()
has been added to the -mm mm-unstable branch. Its filename is
kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Subject: kasan: fix Oops due to missing calls to kasan_arch_is_ready()
Date: Thu, 26 Jan 2023 08:04:47 +0100
On powerpc64, you can build a kernel with KASAN as soon as you build it
with RADIX MMU support. However if the CPU doesn't have RADIX MMU, KASAN
isn't enabled at init and the following Oops is encountered.
[ 0.000000][ T0] KASAN not enabled as it requires radix!
[ 4.484295][ T26] BUG: Unable to handle kernel data access at 0xc00e000000804a04
[ 4.485270][ T26] Faulting instruction address: 0xc00000000062ec6c
[ 4.485748][ T26] Oops: Kernel access of bad area, sig: 11 [#1]
[ 4.485920][ T26] BE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 4.486259][ T26] Modules linked in:
[ 4.486637][ T26] CPU: 0 PID: 26 Comm: kworker/u2:2 Not tainted 6.2.0-rc3-02590-gf8a023b0a805 #249
[ 4.486907][ T26] Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,HEAD pSeries
[ 4.487445][ T26] Workqueue: eval_map_wq .tracer_init_tracefs_work_func
[ 4.488744][ T26] NIP: c00000000062ec6c LR: c00000000062bb84 CTR: c0000000002ebcd0
[ 4.488867][ T26] REGS: c0000000049175c0 TRAP: 0380 Not tainted (6.2.0-rc3-02590-gf8a023b0a805)
[ 4.489028][ T26] MSR: 8000000002009032 <SF,VEC,EE,ME,IR,DR,RI> CR: 44002808 XER: 00000000
[ 4.489584][ T26] CFAR: c00000000062bb80 IRQMASK: 0
[ 4.489584][ T26] GPR00: c0000000005624d4 c000000004917860 c000000001cfc000 1800000000804a04
[ 4.489584][ T26] GPR04: c0000000003a2650 0000000000000cc0 c00000000000d3d8 c00000000000d3d8
[ 4.489584][ T26] GPR08: c0000000049175b0 a80e000000000000 0000000000000000 0000000017d78400
[ 4.489584][ T26] GPR12: 0000000044002204 c000000003790000 c00000000435003c c0000000043f1c40
[ 4.489584][ T26] GPR16: c0000000043f1c68 c0000000043501a0 c000000002106138 c0000000043f1c08
[ 4.489584][ T26] GPR20: c0000000043f1c10 c0000000043f1c20 c000000004146c40 c000000002fdb7f8
[ 4.489584][ T26] GPR24: c000000002fdb834 c000000003685e00 c000000004025030 c000000003522e90
[ 4.489584][ T26] GPR28: 0000000000000cc0 c0000000003a2650 c000000004025020 c000000004025020
[ 4.491201][ T26] NIP [c00000000062ec6c] .kasan_byte_accessible+0xc/0x20
[ 4.491430][ T26] LR [c00000000062bb84] .__kasan_check_byte+0x24/0x90
[ 4.491767][ T26] Call Trace:
[ 4.491941][ T26] [c000000004917860] [c00000000062ae70] .__kasan_kmalloc+0xc0/0x110 (unreliable)
[ 4.492270][ T26] [c0000000049178f0] [c0000000005624d4] .krealloc+0x54/0x1c0
[ 4.492453][ T26] [c000000004917990] [c0000000003a2650] .create_trace_option_files+0x280/0x530
[ 4.492613][ T26] [c000000004917a90] [c000000002050d90] .tracer_init_tracefs_work_func+0x274/0x2c0
[ 4.492771][ T26] [c000000004917b40] [c0000000001f9948] .process_one_work+0x578/0x9f0
[ 4.492927][ T26] [c000000004917c30] [c0000000001f9ebc] .worker_thread+0xfc/0x950
[ 4.493084][ T26] [c000000004917d60] [c00000000020be84] .kthread+0x1a4/0x1b0
[ 4.493232][ T26] [c000000004917e10] [c00000000000d3d8] .ret_from_kernel_thread+0x58/0x60
[ 4.495642][ T26] Code: 60000000 7cc802a6 38a00000 4bfffc78 60000000 7cc802a6 38a00001 4bfffc68 60000000 3d20a80e 7863e8c2 792907c6 <7c6348ae> 20630007 78630fe0 68630001
[ 4.496704][ T26] ---[ end trace 0000000000000000 ]---
The Oops is due to kasan_byte_accessible() not checking the readiness of
KASAN. Add missing call to kasan_arch_is_ready() and bail out when not
ready. The same problem is observed with ____kasan_kfree_large() so fix
it the same.
Also, as KASAN is not available and no shadow area is allocated for linear
memory mapping, there is no point in allocating shadow mem for vmalloc
memory as shown below in /sys/kernel/debug/kernel_page_tables
---[ kasan shadow mem start ]---
0xc00f000000000000-0xc00f00000006ffff 0x00000000040f0000 448K r w pte valid present dirty accessed
0xc00f000000860000-0xc00f00000086ffff 0x000000000ac10000 64K r w pte valid present dirty accessed
0xc00f3ffffffe0000-0xc00f3fffffffffff 0x0000000004d10000 128K r w pte valid present dirty accessed
---[ kasan shadow mem end ]---
So, also verify KASAN readiness before allocating and poisoning
shadow mem for VMAs.
Link: https://lkml.kernel.org/r/150768c55722311699fdcf8f5379e8256749f47d.1674716617.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reported-by: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/common.c | 3 +++
mm/kasan/generic.c | 7 ++++++-
mm/kasan/shadow.c | 12 ++++++++++++
3 files changed, 21 insertions(+), 1 deletion(-)
--- a/mm/kasan/common.c~kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready
+++ a/mm/kasan/common.c
@@ -246,6 +246,9 @@ bool __kasan_slab_free(struct kmem_cache
static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
{
+ if (!kasan_arch_is_ready())
+ return false;
+
if (ptr != page_address(virt_to_head_page(ptr))) {
kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
return true;
--- a/mm/kasan/generic.c~kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready
+++ a/mm/kasan/generic.c
@@ -191,7 +191,12 @@ bool kasan_check_range(unsigned long add
bool kasan_byte_accessible(const void *addr)
{
- s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
+ s8 shadow_byte;
+
+ if (!kasan_arch_is_ready())
+ return true;
+
+ shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE;
}
--- a/mm/kasan/shadow.c~kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready
+++ a/mm/kasan/shadow.c
@@ -291,6 +291,9 @@ int kasan_populate_vmalloc(unsigned long
unsigned long shadow_start, shadow_end;
int ret;
+ if (!kasan_arch_is_ready())
+ return 0;
+
if (!is_vmalloc_or_module_addr((void *)addr))
return 0;
@@ -459,6 +462,9 @@ void kasan_release_vmalloc(unsigned long
unsigned long region_start, region_end;
unsigned long size;
+ if (!kasan_arch_is_ready())
+ return;
+
region_start = ALIGN(start, KASAN_MEMORY_PER_SHADOW_PAGE);
region_end = ALIGN_DOWN(end, KASAN_MEMORY_PER_SHADOW_PAGE);
@@ -502,6 +508,9 @@ void *__kasan_unpoison_vmalloc(const voi
* with setting memory tags, so the KASAN_VMALLOC_INIT flag is ignored.
*/
+ if (!kasan_arch_is_ready())
+ return (void *)start;
+
if (!is_vmalloc_or_module_addr(start))
return (void *)start;
@@ -524,6 +533,9 @@ void *__kasan_unpoison_vmalloc(const voi
*/
void __kasan_poison_vmalloc(const void *start, unsigned long size)
{
+ if (!kasan_arch_is_ready())
+ return;
+
if (!is_vmalloc_or_module_addr(start))
return;
_
Patches currently in -mm which might be from christophe.leroy@xxxxxxxxxx are
kasan-fix-oops-due-to-missing-calls-to-kasan_arch_is_ready.patch
