[syzbot] [io-uring?] [mm?] general protection fault in lock_vma_under_rcu

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e5d3fd687aac Add linux-next specific files for 20250218
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1643b498580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e945b2fe8e5992f
dashboard link: https://syzkaller.appspot.com/bug?extid=556fda2d78f9b0daa141
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=138207a4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ef079ccd2725/disk-e5d3fd68.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/99f2123d6831/vmlinux-e5d3fd68.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eadfc9520358/bzImage-e5d3fd68.xz

The issue was bisected to:

commit 0670f2f4d6ff1cd6aa351389130ba7bbafb02320
Author: Suren Baghdasaryan <sur...@google.com>
Date: Thu Feb 13 22:46:49 2025 +0000

mm: replace vm_lock and detached flag with a reference count

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1355bfdf980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=10d5bfdf980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1755bfdf980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+556fda...@syzkaller.appspotmail.com
Fixes: 0670f2f4d6ff ("mm: replace vm_lock and detached flag with a reference count")

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 27018 Comm: syz.1.4414 Not tainted 6.14.0-rc3-next-20250218-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:vma_refcount_put include/linux/mm.h:712 [inline]
RIP: 0010:vma_end_read include/linux/mm.h:811 [inline]
RIP: 0010:lock_vma_under_rcu+0x578/0xac0 mm/memory.c:6454
Code: be 5d b1 ff 49 be 00 00 00 00 00 fc ff df 4d 85 ff 74 0d 49 81 ff 01 f0 ff ff 0f 82 a3 02 00 00 49 83 ff f5 0f 85 55 03 00 00 <41> 80 3e 00 74 0a bf 05 00 00 00 e8 28 df 18 00 4c 8b 34 25 05 00
RSP: 0000:ffffc9000b837d80 EFLAGS: 00010246
RAX: fffffffffffffff5 RBX: 0000000000000000 RCX: ffff888079eb8000
RDX: ffff888079eb8000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000b837ed8 R08: ffffffff8210a26a R09: 1ffff110068be328
R10: dffffc0000000000 R11: ffffed10068be329 R12: ffffc9000b837e10
R13: ffff88802890aa20 R14: dffffc0000000000 R15: fffffffffffffff5
FS: 00005555908b1500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000400000002fc0 CR3: 0000000011df6000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
do_user_addr_fault arch/x86/mm/fault.c:1328 [inline]
handle_page_fault arch/x86/mm/fault.c:1480 [inline]
exc_page_fault+0x17b/0x920 arch/x86/mm/fault.c:1538
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f617a954ed8
Code: fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 fa 7f 4c 17 f0 c3 66 0f 1f 84 00 00 00 00 00 48 8b 4c 16 f8 48 8b 36 <48> 89 37 48 89 4c 17 f8 c3 c5 fe 6f 54 16 e0 c5 fe 6f 5c 16 c0 c5
RSP: 002b:00007ffc20f24718 EFLAGS: 00010246
RAX: 0000400000002fc0 RBX: 0000000000000004 RCX: 0031313230386c6e
RDX: 0000000000000008 RSI: 0031313230386c6e RDI: 0000400000002fc0
RBP: 0000000000000000 R08: 00007f617a800000 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000009 R12: 00007f617aba5fac
R13: 00007f617aba5fa0 R14: fffffffffffffffe R15: 0000000000000006
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vma_refcount_put include/linux/mm.h:712 [inline]
RIP: 0010:vma_end_read include/linux/mm.h:811 [inline]
RIP: 0010:lock_vma_under_rcu+0x578/0xac0 mm/memory.c:6454
Code: be 5d b1 ff 49 be 00 00 00 00 00 fc ff df 4d 85 ff 74 0d 49 81 ff 01 f0 ff ff 0f 82 a3 02 00 00 49 83 ff f5 0f 85 55 03 00 00 <41> 80 3e 00 74 0a bf 05 00 00 00 e8 28 df 18 00 4c 8b 34 25 05 00
RSP: 0000:ffffc9000b837d80 EFLAGS: 00010246
RAX: fffffffffffffff5 RBX: 0000000000000000 RCX: ffff888079eb8000
RDX: ffff888079eb8000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000b837ed8 R08: ffffffff8210a26a R09: 1ffff110068be328
R10: dffffc0000000000 R11: ffffed10068be329 R12: ffffc9000b837e10
R13: ffff88802890aa20 R14: dffffc0000000000 R15: fffffffffffffff5
FS: 00005555908b1500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff182f3cf98 CR3: 0000000011df6000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 5d pop %rbp
1: b1 ff mov $0xff,%cl
3: 49 be 00 00 00 00 00 movabs $0xdffffc0000000000,%r14
a: fc ff df
d: 4d 85 ff test %r15,%r15
10: 74 0d je 0x1f
12: 49 81 ff 01 f0 ff ff cmp $0xfffffffffffff001,%r15
19: 0f 82 a3 02 00 00 jb 0x2c2
1f: 49 83 ff f5 cmp $0xfffffffffffffff5,%r15
23: 0f 85 55 03 00 00 jne 0x37e
* 29: 41 80 3e 00 cmpb $0x0,(%r14) <-- trapping instruction
2d: 74 0a je 0x39
2f: bf 05 00 00 00 mov $0x5,%edi
34: e8 28 df 18 00 call 0x18df61
39: 4c rex.WR
3a: 8b .byte 0x8b
3b: 34 25 xor $0x25,%al
3d: 05 .byte 0x5


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Edward Adam Davis]

#syz test

diff --git a/mm/memory.c b/mm/memory.c
index d5c4f932b399..a5b1832ec8f6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6492,8 +6492,7 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
if (!vma)
goto inval;

- vma = vma_start_read(mm, vma);
- if (IS_ERR_OR_NULL(vma)) {
+ if (IS_ERR_OR_NULL(vma_start_read(mm, vma))) {
/* Check if the VMA got isolated after we found it */
if (PTR_ERR(vma) == -EAGAIN) {
count_vm_vma_lock_event(VMA_LOCK_MISS);

[Edward Adam Davis]

#syz test

diff --git a/mm/memory.c b/mm/memory.c

index d5c4f932b399..f67670cb2e22 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6484,7 +6484,7 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
unsigned long address)
{
MA_STATE(mas, &mm->mm_mt, address, address);
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *vma2;

rcu_read_lock();
retry:
@@ -6492,10 +6492,10 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,

if (!vma)
goto inval;

- vma = vma_start_read(mm, vma);
- if (IS_ERR_OR_NULL(vma)) {

+ vma2 = vma_start_read(mm, vma);
+ if (IS_ERR_OR_NULL(vma2)) {

/* Check if the VMA got isolated after we found it */

- if (PTR_ERR(vma) == -EAGAIN) {
+ if (PTR_ERR(vma2) == -EAGAIN) {
count_vm_vma_lock_event(VMA_LOCK_MISS);
/* The area was replaced with another one */
goto retry;

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

<stdin>:4:15: error: use of undeclared identifier '__ref_stack_chk_guard'


Tested on:

commit: 0226d0ce Add linux-next specific files for 20250225
git tree: linux-next

kernel config: https://syzkaller.appspot.com/x/.config?x=4e945b2fe8e5992f
dashboard link: https://syzkaller.appspot.com/bug?extid=556fda2d78f9b0daa141
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=128a97a4580000

[syzbot]

patch: https://syzkaller.appspot.com/x/patch.diff?x=15d3c6e4580000

[Shivank Garg]

Hi,

This issue is fixed by this patch:
https://lore.kernel.org/all/20250220200208....@google.com

#syz fix: mm: fix a crash due to vma_end_read() that should have been removed

Thanks,
Shivank

[syzbot]

This bug is marked as fixed by commit:

mm: fix a crash due to vma_end_read() that should have been removed

But I can't find it in the tested trees[1] for more than 90 days.
Is it a correct commit? Please update it by replying:

#syz fix: exact-commit-title

Until then the bug is still considered open and new crashes with
the same signature are ignored.

Kernel: Linux
Dashboard link: https://syzkaller.appspot.com/bug?extid=556fda2d78f9b0daa141

---
[1] I expect the commit to be present in:

1. for-kernelci branch of
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

2. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git

3. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

4. main branch of
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git

The full list of 10 trees can be found at
https://syzkaller.appspot.com/upstream/repos

[Suren Baghdasaryan]

On Mon, May 26, 2025 at 1:50 AM syzbot
<syzbot+556fda...@syzkaller.appspotmail.com> wrote:
>
> This bug is marked as fixed by commit:
> mm: fix a crash due to vma_end_read() that should have been removed
>
> But I can't find it in the tested trees[1] for more than 90 days.
> Is it a correct commit? Please update it by replying:
>
> #syz fix: exact-commit-title

Yeah, the fix was folded into the original patch

#syz fix: mm: replace vm_lock and detached flag with a reference count