[syzbot] [mm?] kernel BUG in __page_table_check_zero

[syzbot] [mm?] kernel BUG in __page_table_check_zero

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    1b66c114d161 Merge tag 'nfsd-6.4-1' of git://git.kernel.or..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10ef2e5a280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ac0db1213414a978
dashboard link: https://syzkaller.appspot.com/bug?extid=7a9bbb158a7a1071eb27
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136b9e86280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11a85bd6280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ac769e66fb5a/disk-1b66c114.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bee287306a14/vmlinux-1b66c114.xz
kernel image: https://storage.googleapis.com/syzbot-assets/342e345ae447/bzImage-1b66c114.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7a9bbb158a7a1071eb27@syzkaller.appspotmail.com

RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fec20228c89
RDX: 0000000001000002 RSI: 0000000000400000 RDI: 0000000020000000
RBP: 00007fff16e19850 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000011012 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
------------[ cut here ]------------
kernel BUG at mm/page_table_check.c:142!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5004 Comm: syz-executor464 Not tainted 6.4.0-rc2-syzkaller-00015-g1b66c114d161 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
RIP: 0010:__page_table_check_zero+0x175/0x1c0 mm/page_table_check.c:142
Code: 24 08 80 38 00 75 47 48 03 2d f7 d4 04 10 49 83 c4 01 e9 00 ff ff ff e8 79 50 a2 ff 0f 0b e8 72 50 a2 ff 0f 0b e8 6b 50 a2 ff <0f> 0b e8 64 50 a2 ff 0f 0b e8 5d 50 a2 ff 48 89 ef 48 83 c4 10 5b
RSP: 0018:ffffc90003b3fa10 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff8880220c0000 RSI: ffffffff81e1f265 RDI: 0000000000000005
RBP: ffff888016090000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 1ffffffff18f47c1 R12: 0000000000000000
R13: 000000000000000a R14: 0000000000000400 R15: dffffc0000000000
FS:  00005555572c2300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000064392c CR3: 000000007abec000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 page_table_check_free include/linux/page_table_check.h:46 [inline]
 free_pages_prepare mm/page_alloc.c:1303 [inline]
 __free_pages_ok+0x9c8/0x1060 mm/page_alloc.c:1441
 hcd_buffer_free+0x1b9/0x250 drivers/usb/core/buffer.c:163
 usb_free_coherent+0x6b/0x80 drivers/usb/core/usb.c:1035
 dec_usb_memory_use_count+0x253/0x3f0 drivers/usb/core/devio.c:197
 usbdev_mmap+0x8d8/0xc40 drivers/usb/core/devio.c:277
 call_mmap include/linux/fs.h:1873 [inline]
 mmap_region+0x694/0x28d0 mm/mmap.c:2652
 do_mmap+0x831/0xf60 mm/mmap.c:1394
 vm_mmap_pgoff+0x1a2/0x3b0 mm/util.c:543
 ksys_mmap_pgoff+0x41f/0x5a0 mm/mmap.c:1440
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fec20228c89
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff16e19838 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fec20228c89
RDX: 0000000001000002 RSI: 0000000000400000 RDI: 0000000020000000
RBP: 00007fff16e19850 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000011012 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__page_table_check_zero+0x175/0x1c0 mm/page_table_check.c:142
Code: 24 08 80 38 00 75 47 48 03 2d f7 d4 04 10 49 83 c4 01 e9 00 ff ff ff e8 79 50 a2 ff 0f 0b e8 72 50 a2 ff 0f 0b e8 6b 50 a2 ff <0f> 0b e8 64 50 a2 ff 0f 0b e8 5d 50 a2 ff 48 89 ef 48 83 c4 10 5b
RSP: 0018:ffffc90003b3fa10 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff8880220c0000 RSI: ffffffff81e1f265 RDI: 0000000000000005
RBP: ffff888016090000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 1ffffffff18f47c1 R12: 0000000000000000
R13: 000000000000000a R14: 0000000000000400 R15: dffffc0000000000
FS:  00005555572c2300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056248b8b7008 CR3: 000000007abec000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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 syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, 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 change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

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

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

Re: [syzbot] Discardable change

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Discardable change
Author: yuran.pereira@hotmail.com

#syz test:
https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 drivers/usb/core/devio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 3beb6a862e80..22ae7babf46b 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -276,12 +276,14 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
 		if (remap_pfn_range(vma, vma->vm_start,
 				    virt_to_phys(usbm->mem) >> PAGE_SHIFT,
 				    size, vma->vm_page_prot) < 0) {
+			pr_info("==> if* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
 	} else {
 		if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle,
 				      size)) {
+			pr_info("==> else* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
-- 
2.25.1

Re: [syzbot] Discardable change

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Discardable change
Author: yuran.pereira@hotmail.com

#syz test: https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 drivers/usb/core/devio.c | 2 ++
 include/linux/page_ext.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 3beb6a862e80..22ae7babf46b 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -276,12 +276,14 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
 		if (remap_pfn_range(vma, vma->vm_start,
 				    virt_to_phys(usbm->mem) >> PAGE_SHIFT,
 				    size, vma->vm_page_prot) < 0) {
+			pr_info("==> if* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
 	} else {
 		if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle,
 				      size)) {
+			pr_info("==> else* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index be98564191e6..fb3e7dcfbffb 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -84,6 +84,7 @@ extern void page_ext_put(struct page_ext *page_ext);
 static inline void *page_ext_data(struct page_ext *page_ext,
 				  struct page_ext_operations *ops)
 {
+	pr_info("==> offset = %ld\n", ops->offset);
 	return (void *)(page_ext) + ops->offset;
 }
 
-- 
2.25.1

Re: [syzbot] Discardable change

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Discardable change
Author: yuran.pereira@hotmail.com

#syz test: https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 drivers/usb/core/devio.c | 2 ++
 mm/page_table_check.c    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 3beb6a862e80..22ae7babf46b 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -276,12 +276,14 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma)
 		if (remap_pfn_range(vma, vma->vm_start,
 				    virt_to_phys(usbm->mem) >> PAGE_SHIFT,
 				    size, vma->vm_page_prot) < 0) {
+			pr_info("==> if* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
 	} else {
 		if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle,
 				      size)) {
+			pr_info("==> else* vma_use_count %d\n", usbm->vma_use_count);
 			dec_usb_memory_use_count(usbm, &usbm->vma_use_count);
 			return -EAGAIN;
 		}
diff --git a/mm/page_table_check.c b/mm/page_table_check.c
index af69c3c8f7c2..ef0fb410cf10 100644
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c
@@ -142,6 +142,8 @@ void __page_table_check_zero(struct page *page, unsigned int order)
 	for (i = 0; i < (1ul << order); i++) {
 		struct page_table_check *ptc = get_page_table_check(page_ext);
 
+		pr_info("===> anon check_zero %d\n", atomic_read(&ptc->anon_map_count));
+		pr_info("===> fmap check_zero %d\n", atomic_read(&ptc->file_map_count));
 		BUG_ON(atomic_read(&ptc->anon_map_count));
 		BUG_ON(atomic_read(&ptc->file_map_count));
 		page_ext = page_ext_next(page_ext);
-- 
2.25.1

Re: [syzbot] [usb] kernel BUG in __page_table_check_zero

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 79a61cc3fc0466ad2b7b89618a6157785f0293b3
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu Sep 12 00:11:23 2024 +0000

    mm: avoid leaving partial pfn mappings around in error case

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11f76c87980000
start commit:   cbf3a2cb156a Merge tag 'nfs-for-6.6-3' of git://git.linux-..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=57da1ac039c4c78a
dashboard link: https://syzkaller.appspot.com/bug?extid=7a9bbb158a7a1071eb27
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15394721680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=152b7af6680000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: mm: avoid leaving partial pfn mappings around in error case

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [usb] kernel BUG in __page_table_check_zero

[Linus Torvalds]

#syz fix: mm: avoid leaving partial pfn mappings around in error case

Because even if I wasn't aware of the syzbot report, it does look like
a match for what the commit was meant to fix (and may have been the
source of Jann's report).

             Linus

On Sun, 20 Oct 2024 at 11:12, syzbot
<syzbot+7a9bbb158a7a1071eb27@syzkaller.appspotmail.com> wrote:
>
> If the result looks correct, please mark the issue as fixed by replying with:
>
> #syz fix: mm: avoid leaving partial pfn mappings around in error case

Re: [syzbot] [usb] kernel BUG in __page_table_check_zero

[Jann Horn]

On Sun, Oct 20, 2024 at 10:32 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> Because even if I wasn't aware of the syzbot report, it does look like
> a match for what the commit was meant to fix (and may have been the
> source of Jann's report).

Huh, I had no idea syzkaller had already found this one... neat.