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Fri, 4 Sep 2020 23:35:57 +0000 (UTC) X-HE-Tag: wine62_3811e61270b6 X-Filterd-Recvd-Size: 5856 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Sep 2020 23:35:56 +0000 (UTC) Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A5B452084D; Fri, 4 Sep 2020 23:35:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599262555; bh=01S+J4BG+Uf2gR8LLsPpEO4B5nFRQXzksXiZYB5ydhY=; h=Date:From:To:Subject:In-Reply-To:From; b=FJ4qmXIWpL8MhhHxO++lxAQTDhBykVP/EquZz1F/7hXd3y6/4owjeZTCcrJPPadLZ SzpEUXirhFzTCcj3LH+zl/uqDL4TwlI7CHGBCZeGJ4upAjdvMoG4nDP9/l/nK72pUw 8LIIujnVLTb0vLnXnDKi0hN4j8zS3ekJX+nrnSqQ= Date: Fri, 04 Sep 2020 16:35:55 -0700 From: Andrew Morton To: akpm@linux-foundation.org, jack@suse.cz, linux-mm@kvack.org, mm-commits@vger.kernel.org, shy828301@gmail.com, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 11/19] mm: madvise: fix vma user-after-free Message-ID: <20200904233555.nMt3agulD%akpm@linux-foundation.org> In-Reply-To: <20200904163454.4db0e6ce0c4584d2653678a3@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 2C8F86C04 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.035093, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Yang Shi Subject: mm: madvise: fix vma user-after-free The syzbot reported the below use-after-free: BUG: KASAN: use-after-free in madvise_willneed mm/madvise.c:293 [inline] BUG: KASAN: use-after-free in madvise_vma mm/madvise.c:942 [inline] BUG: KASAN: use-after-free in do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145 Read of size 8 at addr ffff8880a6163eb0 by task syz-executor.0/9996 CPU: 0 PID: 9996 Comm: syz-executor.0 Not tainted 5.9.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 madvise_willneed mm/madvise.c:293 [inline] madvise_vma mm/madvise.c:942 [inline] do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145 do_madvise mm/madvise.c:1169 [inline] __do_sys_madvise mm/madvise.c:1171 [inline] __se_sys_madvise mm/madvise.c:1169 [inline] __x64_sys_madvise+0xd9/0x110 mm/madvise.c:1169 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d4d9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f04f7464c78 EFLAGS: 00000246 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 0000000000020800 RCX: 000000000045d4d9 RDX: 0000000000000003 RSI: 0000000000600003 RDI: 0000000020000000 RBP: 000000000118d020 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec R13: 00007ffc579cce7f R14: 00007f04f74659c0 R15: 000000000118cfec Allocated by task 9992: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 slab_post_alloc_hook mm/slab.h:518 [inline] slab_alloc mm/slab.c:3312 [inline] kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482 vm_area_alloc+0x1c/0x110 kernel/fork.c:347 mmap_region+0x8e5/0x1780 mm/mmap.c:1743 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 9992: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 __cache_free mm/slab.c:3418 [inline] kmem_cache_free.part.0+0x67/0x1f0 mm/slab.c:3693 remove_vma+0x132/0x170 mm/mmap.c:184 remove_vma_list mm/mmap.c:2613 [inline] __do_munmap+0x743/0x1170 mm/mmap.c:2869 do_munmap mm/mmap.c:2877 [inline] mmap_region+0x257/0x1780 mm/mmap.c:1716 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 It is because vma is accessed after releasing mmap_lock, but someone else acquired the mmap_lock and the vma is gone. Releasing mmap_lock after accessing vma should fix the problem. Link: https://lkml.kernel.org/r/20200816141204.162624-1-shy828301@gmail.com Fixes: 692fe62433d4c ("mm: Handle MADV_WILLNEED through vfs_fadvise()") Reported-by: syzbot+b90df26038d1d5d85c97@syzkaller.appspotmail.com Signed-off-by: Yang Shi Reviewed-by: Andrew Morton Reviewed-by: Jan Kara Cc: [5.4+] Signed-off-by: Andrew Morton --- mm/madvise.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/madvise.c~mm-madvise-fix-vma-user-after-free +++ a/mm/madvise.c @@ -289,9 +289,9 @@ static long madvise_willneed(struct vm_a */ *prev = NULL; /* tell sys_madvise we drop mmap_lock */ get_file(file); - mmap_read_unlock(current->mm); offset = (loff_t)(start - vma->vm_start) + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); + mmap_read_unlock(current->mm); vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); fput(file); mmap_read_lock(current->mm); _