From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>,
airlied@redhat.com, chris@chris-wilson.co.uk, daniel@ffwll.ch,
jhubbard@nvidia.com, linmiaohe@huawei.com, linux-mm@kvack.org,
louhongxiang@huawei.com, mm-commits@vger.kernel.org,
sumit.semwal@linaro.org, torvalds@linux-foundation.org,
willy@infradead.org
Subject: Re: [patch 3/5] mm: mmap: fix general protection fault in unlink_file_vma()
Date: Mon, 12 Oct 2020 14:19:44 +0200 [thread overview]
Message-ID: <7b38790e-9515-f849-ad70-458d5f081651@gmail.com> (raw)
In-Reply-To: <20201011061634.E2EVnOdUx%akpm@linux-foundation.org>
Am 11.10.20 um 08:16 schrieb Andrew Morton:
> From: Miaohe Lin <linmiaohe@huawei.com>
> Subject: mm: mmap: Fix general protection fault in unlink_file_vma()
>
> The syzbot reported the below general protection fault:
>
> general protection fault, probably for non-canonical address
> 0xe00eeaee0000003b: 0000 [#1] PREEMPT SMP KASAN
> KASAN: maybe wild-memory-access in range
> [0x00777770000001d8-0x00777770000001df]
> CPU: 1 PID: 10488 Comm: syz-executor721 Not tainted 5.9.0-rc3-syzkaller #0
> RIP: 0010:unlink_file_vma+0x57/0xb0 mm/mmap.c:164
> Code: 4c 8b a5 a0 00 00 00 4d 85 e4 74 4e e8 92 d7 cd ff 49 8d bc 24
> d8 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c
> 02 00 75 3d 4d 8b b4 24 d8 01 00 00 4d 8d 6e 78 4c 89 ef e8
> RSP: 0018:ffffc9000ac0f9b0 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff88800010ceb0 RCX: ffffffff81592421
> RDX: 000eeeee0000003b RSI: ffffffff81a6736e RDI: 00777770000001d8
> RBP: ffff88800010ceb0 R08: 0000000000000001 R09: ffff88801291a50f
> R10: ffffed10025234a1 R11: 0000000000000001 R12: 0077777000000000
> R13: 00007f1eea0da000 R14: 00007f1eea0d9000 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff8880ae700000(0000)
> knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f1eea11a9d0 CR3: 000000000007e000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> free_pgtables+0x1b3/0x2f0 mm/memory.c:415
> exit_mmap+0x2c0/0x530 mm/mmap.c:3184
> __mmput+0x122/0x470 kernel/fork.c:1076
> mmput+0x53/0x60 kernel/fork.c:1097
> exit_mm kernel/exit.c:483 [inline]
> do_exit+0xa8b/0x29f0 kernel/exit.c:793
> do_group_exit+0x125/0x310 kernel/exit.c:903
> get_signal+0x428/0x1f00 kernel/signal.c:2757
> arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811
> exit_to_user_mode_loop kernel/entry/common.c:136 [inline]
> exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:167
> syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:242
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> It's because the ->mmap() callback can change vma->vm_file and fput the
> original file. But the commit d70cec898324 ("mm: mmap: merge vma after
> call_mmap() if possible") failed to catch this case and always fput() the
> original file, hence add an extra fput().
>
> [ Thanks Hillf for pointing this extra fput() out. ]
>
> Link: https://lkml.kernel.org/r/20200916090733.31427-1-linmiaohe@huawei.com
> Fixes: d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible")
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> Reported-by: syzbot+c5d5a51dcbb558ca0cb5@syzkaller.appspotmail.com
> Cc: Christian König <ckoenig.leichtzumerken@gmail.com>
> Cc: Hongxiang Lou <louhongxiang@huawei.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
> ---
>
> mm/mmap.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> --- a/mm/mmap.c~mm-mmap-fix-general-protection-fault-in-unlink_file_vma
> +++ a/mm/mmap.c
> @@ -1781,7 +1781,11 @@ unsigned long mmap_region(struct file *f
> merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
> NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
> if (merge) {
> - fput(file);
> + /* ->mmap() can change vma->vm_file and fput the original file. So
> + * fput the vma->vm_file here or we would add an extra fput for file
> + * and cause general protection fault ultimately.
> + */
> + fput(vma->vm_file);
> vm_area_free(vma);
> vma = merge;
> /* Update vm_flags and possible addr to pick up the change. We don't
> _
next prev parent reply other threads:[~2020-10-12 12:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-11 6:15 incoming Andrew Morton
2020-10-11 6:16 ` [patch 1/5] MAINTAINERS: change hardening mailing list Andrew Morton
2020-10-11 6:16 ` [patch 2/5] MAINTAINERS: Antoine Tenart's email address Andrew Morton
2020-10-11 6:16 ` [patch 3/5] mm: mmap: fix general protection fault in unlink_file_vma() Andrew Morton
2020-10-12 12:19 ` Christian König [this message]
2020-10-11 6:16 ` [patch 4/5] mm: validate inode in mapping_set_error() Andrew Morton
2020-10-11 6:16 ` [patch 5/5] mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged Andrew Morton
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