Re: [syzbot] [9p?] KASAN: wild-memory-access Write in v9fs_get_acl

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: wild-memory-access Write in v9fs_get_acl

loop0: detected capacity change from 0 to 256
MINIX-fs: mounting unchecked file system, running fsck is recommended
==================================================================
BUG: KASAN: wild-memory-access in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: wild-memory-access in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
BUG: KASAN: wild-memory-access in __refcount_sub_and_test include/linux/refcount.h:272 [inline]
BUG: KASAN: wild-memory-access in __refcount_dec_and_test include/linux/refcount.h:315 [inline]
BUG: KASAN: wild-memory-access in refcount_dec_and_test include/linux/refcount.h:333 [inline]
BUG: KASAN: wild-memory-access in posix_acl_release include/linux/posix_acl.h:57 [inline]
BUG: KASAN: wild-memory-access in v9fs_get_acl+0x1a4/0x390 fs/9p/acl.c:102
Write of size 4 at addr 9fffeb37f97f1c00 by task syz-executor.0/6490

CPU: 0 PID: 6490 Comm: syz-executor.0 Not tainted 6.3.0-rc1-syzkaller-00230-gef5f68cc1f82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 print_report+0xe4/0x514 mm/kasan/report.c:433
 kasan_report+0xd4/0x130 mm/kasan/report.c:536
 kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:187
 __kasan_check_write+0x2c/0x3c mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
 atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 posix_acl_release include/linux/posix_acl.h:57 [inline]
 v9fs_get_acl+0x1a4/0x390 fs/9p/acl.c:102
 v9fs_mount+0x77c/0xa5c fs/9p/vfs_super.c:183
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
 vfs_get_tree+0x90/0x274 fs/super.c:1501
 do_new_mount+0x25c/0x8c8 fs/namespace.c:3042
 path_mount+0x590/0xe20 fs/namespace.c:3372
 do_mount fs/namespace.c:3385 [inline]
 __do_sys_mount fs/namespace.c:3594 [inline]
 __se_sys_mount fs/namespace.c:3571 [inline]
 __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3571
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
==================================================================
Unable to handle kernel paging request at virtual address 9fffeb37f97f1c00
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004
  CM = 0, WnR = 0
[9fffeb37f97f1c00] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 6490 Comm: syz-executor.0 Tainted: G    B              6.3.0-rc1-syzkaller-00230-gef5f68cc1f82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lse_atomic_fetch_add_release arch/arm64/include/asm/atomic_lse.h:62 [inline]
pc : __lse_atomic_fetch_sub_release arch/arm64/include/asm/atomic_lse.h:76 [inline]
pc : arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline]
pc : atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline]
pc : __refcount_sub_and_test include/linux/refcount.h:272 [inline]
pc : __refcount_dec_and_test include/linux/refcount.h:315 [inline]
pc : refcount_dec_and_test include/linux/refcount.h:333 [inline]
pc : posix_acl_release include/linux/posix_acl.h:57 [inline]
pc : v9fs_get_acl+0x1b0/0x390 fs/9p/acl.c:102
lr : arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline]
lr : atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline]
lr : __refcount_sub_and_test include/linux/refcount.h:272 [inline]
lr : __refcount_dec_and_test include/linux/refcount.h:315 [inline]
lr : refcount_dec_and_test include/linux/refcount.h:333 [inline]
lr : posix_acl_release include/linux/posix_acl.h:57 [inline]
lr : v9fs_get_acl+0x1ac/0x390 fs/9p/acl.c:102
sp : ffff80001e837970
x29: ffff80001e837970 x28: dfff800000000000 x27: 1ffff00003d06f3c
x26: 1ffff00003d06f38 x25: ffff0000dd9041e0 x24: ffff0000dd904178
x23: ffff0000e5068000 x22: dfff800000000000 x21: 9fffeb37f97f1c00
x20: 00000000fffffffb x19: fffffffffffffffb x18: 1fffe000368951b6
x17: ffff800015cdd000 x16: ffff80001245e54c x15: 0000000000000000
x14: 0000000040000000 x13: 0000000000000002 x12: 0000000000000001
x11: ff80800009d819b8 x10: 0000000000000000 x9 : ffff800009d819b8
x8 : 00000000ffffffff x7 : 1fffe000368951b7 x6 : ffff80000828dc14
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000081bc3c4
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 arch_atomic_fetch_sub_release arch/arm64/include/asm/atomic.h:51 [inline]
 atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 posix_acl_release include/linux/posix_acl.h:57 [inline]
 v9fs_get_acl+0x1b0/0x390 fs/9p/acl.c:102
 v9fs_mount+0x77c/0xa5c fs/9p/vfs_super.c:183
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
 vfs_get_tree+0x90/0x274 fs/super.c:1501
 do_new_mount+0x25c/0x8c8 fs/namespace.c:3042
 path_mount+0x590/0xe20 fs/namespace.c:3372
 do_mount fs/namespace.c:3385 [inline]
 __do_sys_mount fs/namespace.c:3594 [inline]
 __se_sys_mount fs/namespace.c:3571 [inline]
 __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3571
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
Code: 97b021c6 d503201f 979e3dbf 12800008 (b86802b6) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	97b021c6 	bl	0xfffffffffec08718
   4:	d503201f 	nop
   8:	979e3dbf 	bl	0xfffffffffe78f704
   c:	12800008 	mov	w8, #0xffffffff            	// #-1
* 10:	b86802b6 	ldaddl	w8, w22, [x21] <-- trapping instruction


Tested on:

commit:         ef5f68cc Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=115a390ac80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fd3c6e109ff25818
dashboard link: https://syzkaller.appspot.com/bug?extid=cb1d16facb3cc90de5fb
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

Note: no patches were applied.