Message-ID: <ZtZ9euGTU9T0PWDA@xpf.sh.intel.com>
Date: Tue, 3 Sep 2024 11:07:38 +0800
From: Pengfei Xu <pengfei.xu@...el.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>
CC: Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, Suren Baghdasaryan <surenb@...gle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Matthew Wilcox
	<willy@...radead.org>, Vlastimil Babka <vbabka@...e.cz>,
	<sidhartha.kumar@...cle.com>, Bert Karwatzki <spasswolf@....de>, Jiri Olsa
	<olsajiri@...il.com>, Kees Cook <kees@...nel.org>, "Paul E . McKenney"
	<paulmck@...nel.org>, Jeff Xu <jeffxu@...omium.org>,
	<syzkaller-bugs@...glegroups.com>
Subject: Re: [PATCH v8 15/21] mm: Change failure of MAP_FIXED to restoring
 the gap on failure

Hi Liam R. Howlett,

Greetings!

There is WARNING in __split_vma in next-20240902 in syzkaller fuzzing test.
Bisected and found first bad commit:
"
3483c95414f9 mm: change failure of MAP_FIXED to restoring the gap on failure
"
It's same as below patch.
After reverted the above commit on top of next-20240902, this issue was gone.

All detailed info: https://github.com/xupengfe/syzkaller_logs/tree/main/240903_092137___split_vma
Syzkaller repro code: https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/repro.c
Syzkaller repro syscall steps: https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/repro.prog
Syzkaller report: https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/repro.report
Kconfig(make olddefconfig): https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/kconfig_origin
Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/bisect_info.log
bzImage: https://github.com/xupengfe/syzkaller_logs/raw/main/240903_092137___split_vma/bzImage_ecc768a84f0b8e631986f9ade3118fa37852fef0.tar.gz
Issue dmesg: https://github.com/xupengfe/syzkaller_logs/blob/main/240903_092137___split_vma/ecc768a84f0b8e631986f9ade3118fa37852fef0_dmesg.log

And "KASAN: slab-use-after-free Read in acct_collect" also pointed to the
same commit, all detailed info:
https://github.com/xupengfe/syzkaller_logs/tree/main/240903_090000_acct_collect

"
[   19.953726] cgroup: Unknown subsys name 'net'
[   20.045121] cgroup: Unknown subsys name 'rlimit'
[   20.138332] ------------[ cut here ]------------
[   20.138634] WARNING: CPU: 1 PID: 732 at include/linux/maple_tree.h:733 __split_vma+0x4d7/0x1020
[   20.139075] Modules linked in:
[   20.139245] CPU: 1 UID: 0 PID: 732 Comm: repro Not tainted 6.11.0-rc6-next-20240902-ecc768a84f0b #1
[   20.139779] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
[   20.140337] RIP: 0010:__split_vma+0x4d7/0x1020
[   20.140572] Code: 89 ee 48 8b 40 10 48 89 c7 48 89 85 00 ff ff ff e8 8e 61 a7 ff 48 8b 85 00 ff ff ff 4c 39 e8 0f 83 ea fd ff ff e8 b9 5e a7 ff <0f> 0b e9 de fd ff ff 48 8b 85 30 ff ff ff 48 83 c0 10 48 89 85 18
[   20.141476] RSP: 0018:ffff8880217379a0 EFLAGS: 00010293
[   20.141749] RAX: 0000000000000000 RBX: ffff8880132351e0 RCX: ffffffff81bf6117
[   20.142106] RDX: ffff888012c30000 RSI: ffffffff81bf6187 RDI: 0000000000000006
[   20.142457] RBP: ffff888021737aa0 R08: 0000000000000001 R09: ffffed100263d3cd
[   20.142814] R10: 0000000020ff9000 R11: 0000000000000001 R12: ffff888021737e40
[   20.143173] R13: 0000000020ff9000 R14: 0000000020ffc000 R15: ffff888013235d20
[   20.143529] FS:  00007eff937f9740(0000) GS:ffff88806c500000(0000) knlGS:0000000000000000
[   20.144308] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   20.144600] CR2: 0000000020000040 CR3: 000000001f464003 CR4: 0000000000770ef0
[   20.144958] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   20.145313] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400
[   20.145665] PKRU: 55555554
[   20.145809] Call Trace:
[   20.145940]  <TASK>
[   20.146056]  ? show_regs+0x6d/0x80
[   20.146247]  ? __warn+0xf3/0x380
[   20.146431]  ? report_bug+0x25e/0x4b0
[   20.146650]  ? __split_vma+0x4d7/0x1020
[   20.146864]  ? report_bug+0x2cb/0x4b0
[   20.147070]  ? __split_vma+0x4d7/0x1020
[   20.147281]  ? __split_vma+0x4d8/0x1020
[   20.147492]  ? handle_bug+0xf1/0x190
[   20.147756]  ? exc_invalid_op+0x3c/0x80
[   20.147971]  ? asm_exc_invalid_op+0x1f/0x30
[   20.148208]  ? __split_vma+0x467/0x1020
[   20.148417]  ? __split_vma+0x4d7/0x1020
[   20.148628]  ? __split_vma+0x4d7/0x1020
[   20.148845]  ? __pfx___split_vma+0x10/0x10
[   20.149068]  ? __kasan_check_read+0x15/0x20
[   20.149300]  ? mark_lock.part.0+0xf3/0x17b0
[   20.149535]  ? __kasan_check_read+0x15/0x20
[   20.149769]  vms_gather_munmap_vmas+0x178/0xf70
[   20.150024]  do_vmi_align_munmap+0x26e/0x640
[   20.150257]  ? __pfx___lock_acquire+0x10/0x10
[   20.150500]  ? __pfx_do_vmi_align_munmap+0x10/0x10
[   20.150758]  ? __this_cpu_preempt_check+0x21/0x30
[   20.151018]  ? __sanitizer_cov_trace_const_cmp4+0x1a/0x20
[   20.151308]  ? mtree_range_walk+0x728/0xb70
[   20.151602]  ? __sanitizer_cov_trace_const_cmp4+0x1a/0x20
[   20.151891]  ? mas_walk+0x6a7/0x8b0
[   20.152096]  do_vmi_munmap+0x202/0x400
[   20.152307]  __vm_munmap+0x182/0x380
[   20.152509]  ? __pfx___vm_munmap+0x10/0x10
[   20.152729]  ? seqcount_lockdep_reader_access.constprop.0+0xb4/0xd0
[   20.153061]  ? lockdep_hardirqs_on+0x89/0x110
[   20.153299]  ? trace_hardirqs_on+0x51/0x60
[   20.153533]  ? __audit_syscall_entry+0x39c/0x500
[   20.153790]  __x64_sys_munmap+0x62/0x90
[   20.154001]  x64_sys_call+0x198f/0x2140
[   20.154212]  do_syscall_64+0x6d/0x140
[   20.154414]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   20.154683] RIP: 0033:0x7eff9343ee5d
[   20.154885] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 8b 0d 93 af 1b 00 f7 d8 64 89 01 48
[   20.155872] RSP: 002b:00007ffe28711628 EFLAGS: 00000206 ORIG_RAX: 000000000000000b
[   20.156267] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007eff9343ee5d
[   20.156635] RDX: ffffffffffffff80 RSI: 0000000000001000 RDI: 0000000020ffc000
[   20.157002] RBP: 00007ffe28711640 R08: 0000000000000000 R09: 00007ffe28711640
[   20.157369] R10: 0000000000000003 R11: 0000000000000206 R12: 00007ffe287117d8
[   20.157737] R13: 00000000004027cc R14: 0000000000404e08 R15: 00007eff93844000
[   20.158122]  </TASK>
[   20.158245] irq event stamp: 2019
[   20.158426] hardirqs last  enabled at (2027): [<ffffffff814629e4>] console_unlock+0x224/0x240
[   20.158869] hardirqs last disabled at (2034): [<ffffffff814629c9>] console_unlock+0x209/0x240
[   20.159306] softirqs last  enabled at (1954): [<ffffffff81289969>] __irq_exit_rcu+0xa9/0x120
[   20.159797] softirqs last disabled at (2051): [<ffffffff81289969>] __irq_exit_rcu+0xa9/0x120
[   20.160233] ---[ end trace 0000000000000000 ]---
"

I hope it's helpful.

Thanks!

---

If you don't need the following environment to reproduce the problem or if you
already have one reproduced environment, please ignore the following information.

How to reproduce:
git clone https://gitlab.com/xupengfe/repro_vm_env.git
cd repro_vm_env
tar -xvf repro_vm_env.tar.gz
cd repro_vm_env; ./start3.sh  // it needs qemu-system-x86_64 and I used v7.1.0
  // start3.sh will load bzImage_2241ab53cbb5cdb08a6b2d4688feb13971058f65 v6.2-rc5 kernel
  // You could change the bzImage_xxx as you want
  // Maybe you need to remove line "-drive if=pflash,format=raw,readonly=on,file=./OVMF_CODE.fd \" for different qemu version
You could use below command to log in, there is no password for root.
ssh -p 10023 root@...alhost

After login vm(virtual machine) successfully, you could transfer reproduced
binary to the vm by below way, and reproduce the problem in vm:
gcc -pthread -o repro repro.c
scp -P 10023 repro root@...alhost:/root/

Get the bzImage for target kernel:
Please use target kconfig and copy it to kernel_src/.config
make olddefconfig
make -jx bzImage           //x should equal or less than cpu num your pc has

Fill the bzImage file into above start3.sh to load the target kernel in vm.

Tips:
If you already have qemu-system-x86_64, please ignore below info.
If you want to install qemu v7.1.0 version:
git clone https://github.com/qemu/qemu.git
cd qemu
git checkout -f v7.1.0
mkdir build
cd build
yum install -y ninja-build.x86_64
yum -y install libslirp-devel.x86_64
../configure --target-list=x86_64-softmmu --enable-kvm --enable-vnc --enable-gtk --enable-sdl --enable-usb-redir --enable-slirp
make
make install

Best Regards,
Thanks!


On 2024-08-30 at 00:00:55 -0400, Liam R. Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> 
> Prior to call_mmap(), the vmas that will be replaced need to clear the
> way for what may happen in the call_mmap().  This clean up work includes
> clearing the ptes and calling the close() vm_ops.  Some users do more
> setup than can be restored by calling the vm_ops open() function.  It is
> safer to store the gap in the vma tree in these cases.
> 
> That is to say that the failure scenario that existed before the
> MAP_FIXED gap exposure is restored as it is safer than trying to undo a
> partial mapping.
> 
> Since abort_munmap_vmas() is only reattaching vmas with this change, the
> function is renamed to reattach_vmas().
> 
> There is also a secondary failure that may occur if there is not enough
> memory to store the gap.  In this case, the vmas are reattached and
> resources freed.  If the system cannot complete the call_mmap() and
> fails to allocate with GFP_KERNEL, then the system will print a warning
> about the failure.
> 
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>  mm/mmap.c |  3 +--
>  mm/vma.c  |  4 +--
>  mm/vma.h  | 80 ++++++++++++++++++++++++++++++++++++++++---------------
>  3 files changed, 61 insertions(+), 26 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 405e0432c78e..e1e5c78b6c3c 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1623,8 +1623,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>  		vm_unacct_memory(charged);
>  
>  abort_munmap:
> -	if (vms.nr_pages)
> -		abort_munmap_vmas(&mas_detach, vms.closed_vm_ops);
> +	vms_abort_munmap_vmas(&vms, &mas_detach);
>  gather_failed:
>  	validate_mm(mm);
>  	return error;
> diff --git a/mm/vma.c b/mm/vma.c
> index 648c58da8ad4..d2d71d659d1e 100644
> --- a/mm/vma.c
> +++ b/mm/vma.c
> @@ -878,7 +878,7 @@ int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,
>  munmap_gather_failed:
>  end_split_failed:
>  modify_vma_failed:
> -	abort_munmap_vmas(mas_detach, /* closed = */ false);
> +	reattach_vmas(mas_detach);
>  start_split_failed:
>  map_count_exceeded:
>  	return error;
> @@ -923,7 +923,7 @@ int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  	return 0;
>  
>  clear_tree_failed:
> -	abort_munmap_vmas(&mas_detach, /* closed = */ false);
> +	reattach_vmas(&mas_detach);
>  gather_failed:
>  	validate_mm(mm);
>  	return error;
> diff --git a/mm/vma.h b/mm/vma.h
> index 64b44f5a0a11..b2306d13d456 100644
> --- a/mm/vma.h
> +++ b/mm/vma.h
> @@ -82,6 +82,22 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  	       unsigned long start, unsigned long end, pgoff_t pgoff);
>  
> +static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
> +			struct vm_area_struct *vma, gfp_t gfp)
> +
> +{
> +	if (vmi->mas.status != ma_start &&
> +	    ((vmi->mas.index > vma->vm_start) || (vmi->mas.last < vma->vm_start)))
> +		vma_iter_invalidate(vmi);
> +
> +	__mas_set_range(&vmi->mas, vma->vm_start, vma->vm_end - 1);
> +	mas_store_gfp(&vmi->mas, vma, gfp);
> +	if (unlikely(mas_is_err(&vmi->mas)))
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
>  #ifdef CONFIG_MMU
>  /*
>   * init_vma_munmap() - Initializer wrapper for vma_munmap_struct
> @@ -129,24 +145,60 @@ void vms_clean_up_area(struct vma_munmap_struct *vms,
>  		struct ma_state *mas_detach, bool mm_wr_locked);
>  
>  /*
> - * abort_munmap_vmas - Undo any munmap work and free resources
> + * reattach_vmas() - Undo any munmap work and free resources
> + * @mas_detach: The maple state with the detached maple tree
>   *
>   * Reattach any detached vmas and free up the maple tree used to track the vmas.
>   */
> -static inline void abort_munmap_vmas(struct ma_state *mas_detach, bool closed)
> +static inline void reattach_vmas(struct ma_state *mas_detach)
>  {
>  	struct vm_area_struct *vma;
>  
>  	mas_set(mas_detach, 0);
> -	mas_for_each(mas_detach, vma, ULONG_MAX) {
> +	mas_for_each(mas_detach, vma, ULONG_MAX)
>  		vma_mark_detached(vma, false);
> -		if (closed && vma->vm_ops && vma->vm_ops->open)
> -			vma->vm_ops->open(vma);
> -	}
>  
>  	__mt_destroy(mas_detach->tree);
>  }
>  
> +/*
> + * vms_abort_munmap_vmas() - Undo as much as possible from an aborted munmap()
> + * operation.
> + * @vms: The vma unmap structure
> + * @mas_detach: The maple state with the detached maple tree
> + *
> + * Reattach any detached vmas, free up the maple tree used to track the vmas.
> + * If that's not possible because the ptes are cleared (and vm_ops->closed() may
> + * have been called), then a NULL is written over the vmas and the vmas are
> + * removed (munmap() completed).
> + */
> +static inline void vms_abort_munmap_vmas(struct vma_munmap_struct *vms,
> +		struct ma_state *mas_detach)
> +{
> +	struct ma_state *mas = &vms->vmi->mas;
> +	if (!vms->nr_pages)
> +		return;
> +
> +	if (vms->clear_ptes)
> +		return reattach_vmas(mas_detach);
> +
> +	/*
> +	 * Aborting cannot just call the vm_ops open() because they are often
> +	 * not symmetrical and state data has been lost.  Resort to the old
> +	 * failure method of leaving a gap where the MAP_FIXED mapping failed.
> +	 */
> +	mas_set_range(mas, vms->start, vms->end);
> +	if (unlikely(mas_store_gfp(mas, NULL, GFP_KERNEL))) {
> +		pr_warn_once("%s: (%d) Unable to abort munmap() operation\n",
> +			     current->comm, current->pid);
> +		/* Leaving vmas detached and in-tree may hamper recovery */
> +		reattach_vmas(mas_detach);
> +	} else {
> +		/* Clean up the insertion of the unfortunate gap */
> +		vms_complete_munmap_vmas(vms, mas_detach);
> +	}
> +}
> +
>  int
>  do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  		    struct mm_struct *mm, unsigned long start,
> @@ -299,22 +351,6 @@ static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
>  	return mas_prev(&vmi->mas, min);
>  }
>  
> -static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
> -			struct vm_area_struct *vma, gfp_t gfp)
> -{
> -	if (vmi->mas.status != ma_start &&
> -	    ((vmi->mas.index > vma->vm_start) || (vmi->mas.last < vma->vm_start)))
> -		vma_iter_invalidate(vmi);
> -
> -	__mas_set_range(&vmi->mas, vma->vm_start, vma->vm_end - 1);
> -	mas_store_gfp(&vmi->mas, vma, gfp);
> -	if (unlikely(mas_is_err(&vmi->mas)))
> -		return -ENOMEM;
> -
> -	return 0;
> -}
> -
> -
>  /*
>   * These three helpers classifies VMAs for virtual memory accounting.
>   */
> -- 
> 2.43.0
> 

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