From nobody Mon Feb 9 05:52:54 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B43E04A08 for ; Thu, 14 Mar 2024 02:05:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710381940; cv=none; b=dwtAe/VNfT/uUXm4c2BK01tdX2DVxXSs97yUdQulHI+HuJtKirj9+1RBh6k++zbP2a3xXRFTJHh8NCgvGOUUWEWwyigyhGHI/zacc/UvkNO51Ri5lSDyBRJedPezUncXp0LJCl1Rt5SjqPHYQuLgUNKKGMiSijJXkf4Cfx05Ve4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710381940; c=relaxed/simple; bh=U7PYq18bfRAU5ibN6PAzHt9sq4pbBVTYfvTtQlSUZlw=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=PQLZqsK2j7PD3AWV41A9KzU9dSp311ZoFxqb7Yrq7gDuUin55Kd5Fi7M1LZSyzmneATWw5zWr0wAF+pTk8xGqKTIG/wyPjeMbbT6bRjrgXfnpqzf9eIE4wkiy23GUo7J4cwW+6OcW7GlH24Z2r2wqpTh1DK4dTZRkL7Do0F7opg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tG8OoOuQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tG8OoOuQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 966EDC433C7; Thu, 14 Mar 2024 02:05:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710381940; bh=U7PYq18bfRAU5ibN6PAzHt9sq4pbBVTYfvTtQlSUZlw=; h=From:To:Cc:Subject:Date:From; b=tG8OoOuQWZabqbTq5kUgMK1AS0e1VYZ40UHH/2aY9rWy9ExRjXLLG8eAcaL4joGxa IepwJt7C4afXJY9ALttZn4h+YFUNvsz3dDtiy4vhtTc4efMpZj52r42ExvGA9ON8iA QJ5Q/5A3omSFYi4tJKAPflQOh97EOcp/Nb9z52HaXyvqWDYeXNFDtM/Mg+ELdySrEF rI74jCaA+29INrSgvSffGgque6QaE5JGzJtzJJs6tbKJl+SyAj/QJKhOpyRGkbDXTQ zAC8H8fpUoRki5d/jCK0uKAvTxM2FEhR7r2L8rLk0FgGNuD6psx92Jko55f9oeAxaH +RcAlbJoMQSRA== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu , syzbot+763afad57075d3f862f2@syzkaller.appspotmail.com, Ed Tsai , Hillf Danton Subject: [PATCH] f2fs: fix to avoid use-after-free issue in f2fs_filemap_fault Date: Thu, 14 Mar 2024 10:05:28 +0800 Message-Id: <20240314020528.3051533-1-chao@kernel.org> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" syzbot reports a f2fs bug as below: BUG: KASAN: slab-use-after-free in f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/fi= le.c:49 Read of size 8 at addr ffff88807bb22680 by task syz-executor184/5058 CPU: 0 PID: 5058 Comm: syz-executor184 Not tainted 6.7.0-syzkaller-09928-g0= 52d534373b7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 11/17/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:377 [inline] print_report+0x163/0x540 mm/kasan/report.c:488 kasan_report+0x142/0x170 mm/kasan/report.c:601 f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/file.c:49 __do_fault+0x131/0x450 mm/memory.c:4376 do_shared_fault mm/memory.c:4798 [inline] do_fault mm/memory.c:4872 [inline] do_pte_missing mm/memory.c:3745 [inline] handle_pte_fault mm/memory.c:5144 [inline] __handle_mm_fault+0x23b7/0x72b0 mm/memory.c:5285 handle_mm_fault+0x27e/0x770 mm/memory.c:5450 do_user_addr_fault arch/x86/mm/fault.c:1364 [inline] handle_page_fault arch/x86/mm/fault.c:1507 [inline] exc_page_fault+0x456/0x870 arch/x86/mm/fault.c:1563 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 The root cause is: in f2fs_filemap_fault(), vmf->vma may be not alive after filemap_fault(), so it may cause use-after-free issue when accessing vmf->vma->vm_flags in trace_f2fs_filemap_fault(). So it needs to keep vm_fl= ags in separated temporary variable for tracepoint use. Fixes: 87f3afd366f7 ("f2fs: add tracepoint for f2fs_vm_page_mkwrite()") Reported-and-tested-by: syzbot+763afad57075d3f862f2@syzkaller.appspotmail.c= om Closes: https://lore.kernel.org/lkml/000000000000e8222b060f00db3b@google.com Cc: Ed Tsai Cc: Hillf Danton Signed-off-by: Chao Yu Suggested-by: Hillf Danton --- fs/f2fs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index a47c57e813bb..c19e55a3e50e 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -39,6 +39,7 @@ static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf) { struct inode *inode =3D file_inode(vmf->vma->vm_file); + vm_flags_t flags =3D vmf->vma->vm_flags; vm_fault_t ret; =20 ret =3D filemap_fault(vmf); @@ -46,7 +47,7 @@ static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf) f2fs_update_iostat(F2FS_I_SB(inode), inode, APP_MAPPED_READ_IO, F2FS_BLKSIZE); =20 - trace_f2fs_filemap_fault(inode, vmf->pgoff, vmf->vma->vm_flags, ret); + trace_f2fs_filemap_fault(inode, vmf->pgoff, flags, ret); =20 return ret; } --=20 2.40.1