Re: [syzbot] [mm?] general protection fault in mas_store_prealloc

[syzbot <syzbot+bc6bfc25a68b7a020ee1@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in mas_store_prealloc

 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Unable to handle kernel paging request at virtual address dfff800000000001
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000001] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 UID: 0 PID: 16112 Comm: syz.0.4215 Not tainted 6.12.0-rc7-syzkaller-00234-g887407160d72 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : mt_slot_locked lib/maple_tree.c:795 [inline]
pc : mas_slot_locked lib/maple_tree.c:808 [inline]
pc : mas_store_prealloc+0x870/0x1068 lib/maple_tree.c:5514
lr : mt_slot_locked lib/maple_tree.c:795 [inline]
lr : mas_slot_locked lib/maple_tree.c:808 [inline]
lr : mas_store_prealloc+0x778/0x1068 lib/maple_tree.c:5514
sp : ffff80009c667440
x29: ffff80009c667560 x28: ffff80009c6674c0 x27: dfff800000000000
x26: ffff7000138cce94 x25: 0000000000000008 x24: 0000000000000000
x23: 0000000000000008 x22: ffff0000dc74f840 x21: 0000000000000008
x20: ffff80009c6678e0 x19: 0000000000000000 x18: 0000000000000008
x17: 0000000000000000 x16: ffff800080585ea8 x15: 0000000000000009
x14: 1ffff000138cce99 x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000138ccea2 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 0000000000000001 x7 : 0000000000000000 x6 : 00000000003bbda8
x5 : ffff80009c6665f8 x4 : 0000000000000008 x3 : ffff80008b4208f0
x2 : ffffffffffffffc0 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
 mt_slot_locked lib/maple_tree.c:795 [inline] (P)
 mas_slot_locked lib/maple_tree.c:808 [inline] (P)
 mas_store_prealloc+0x870/0x1068 lib/maple_tree.c:5514 (P)
 mt_slot_locked lib/maple_tree.c:795 [inline] (L)
 mas_slot_locked lib/maple_tree.c:808 [inline] (L)
 mas_store_prealloc+0x778/0x1068 lib/maple_tree.c:5514 (L)
 vma_iter_store+0x2e8/0x81c mm/vma.h:476
 __mmap_region mm/mmap.c:1513 [inline]
 mmap_region+0x1650/0x1d44 mm/mmap.c:1603
 do_mmap+0x8c4/0xfac mm/mmap.c:496
 vm_mmap_pgoff+0x1a0/0x38c mm/util.c:588
 ksys_mmap_pgoff+0x3a4/0x5c8 mm/mmap.c:542
 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
 __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
 __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Code: 393b2668 972c43de 8b180ef5 d343fea8 (387b6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	393b2668 	strb	w8, [x19, #3785]
   4:	972c43de 	bl	0xfffffffffcb10f7c
   8:	8b180ef5 	add	x21, x23, x24, lsl #3
   c:	d343fea8 	lsr	x8, x21, #3
* 10:	387b6908 	ldrb	w8, [x8, x27] <-- trapping instruction


Tested on:

commit:         88740716 Merge remote-tracking branch 'iommu/arm/smmu'..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=15aed378580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a1eb85a42cb8ccec
dashboard link: https://syzkaller.appspot.com/bug?extid=bc6bfc25a68b7a020ee1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Note: no patches were applied.