From mboxrd@z Thu Jan 1 00:00:00 1970 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 5B6C53164A6; Mon, 3 Nov 2025 16:50:10 +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=1762188611; cv=none; b=pIoRJoFOQuh7y+6jDReaEzn3USBUkYqi+9lsGw9n5daV3idt9TNRCH85ij3J+L00K6/sfbFxl9i5qmMkEWdBKa0UcEYLXBsp8e/cV2Q8cOooTe/EMhFWtnFmmS6kcQbYOFju5V356cD/IEf1deeK7UsjuM5kO90ddL9cpboxe0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762188611; c=relaxed/simple; bh=2NkK38TMc9LjJ8TfBFIjiUuCdo4RLI6/R2QEBQ+3oS8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DAyOhELfHMJEhdm4SVd3jm6DArA438xYUyUlaZKM4LAMOVJEHPW7EpmhTc6BNI8Ku7H7VnzQR15VumYOn1ydEt+mU4+o4UGyc/B2UtwAk7DSt/eYJIv8Wp+MFb4mGC+RiISukzfX1A8qP5rKFkaohC2/2TjF9UrPeXLd3NesJ9M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=i5qHNpgk; 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="i5qHNpgk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8ED4CC4CEE7; Mon, 3 Nov 2025 16:50:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762188610; bh=2NkK38TMc9LjJ8TfBFIjiUuCdo4RLI6/R2QEBQ+3oS8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=i5qHNpgkyZf8G8iPlE8jjG6diw2zsxGCBW5lvorirQt793LgKtv5xy7pJymcJlVjP ORtRmpa9oGl1YgF5PE1t7vQncGFeOGeiZL6yZgfK7Klt5lluGVDve7u70ignIzrdWa AUH+dmArO6hW4d2CF7jDum5fiA7uK3bb9mqiTmN00pUcmeHLcc5j/Kt4C+7RhlV1s3 Hltb/jtTNRl0wjWUzwJIEoJIzhoDiegS+O+eDt81ty0bLZ+G7n6DAPj2AEOfvvrqql o6F/ln8BYfX3HpQ7bqgBKuvAZ6hunRA9BK6YU8OAqKHZ01xfg8ifMbN+CPLLSAHcDC 0wmC7RvGLvH5Q== Date: Mon, 3 Nov 2025 08:48:29 -0800 From: Eric Biggers To: Yongpeng Yang Cc: Jaegeuk Kim , Theodore Ts'o , linux-fscrypt@vger.kernel.org, Yongpeng Yang , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, Luis Chamberlain Subject: Re: [PATCH v2] fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT Message-ID: <20251103164829.GC1735@sol> References: <20251030072956.454679-1-yangyongpeng.storage@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251030072956.454679-1-yangyongpeng.storage@gmail.com> [+linux-fsdevel, linux-block, and Luis] On Thu, Oct 30, 2025 at 03:29:56PM +0800, Yongpeng Yang wrote: > From: Yongpeng Yang > > When simulating an nvme device on qemu with both logical_block_size and > physical_block_size set to 8 KiB, a error trace appears during partition > table reading at boot time. The issue is caused by inode->i_blkbits being > larger than PAGE_SHIFT, which leads to a left shift of -1 and triggering a > UBSAN warning. > > [ 2.697306] ------------[ cut here ]------------ > [ 2.697309] UBSAN: shift-out-of-bounds in fs/crypto/inline_crypt.c:336:37 > [ 2.697311] shift exponent -1 is negative > [ 2.697315] CPU: 3 UID: 0 PID: 274 Comm: (udev-worker) Not tainted 6.18.0-rc2+ #34 PREEMPT(voluntary) > [ 2.697317] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 2.697320] Call Trace: > [ 2.697324] > [ 2.697325] dump_stack_lvl+0x76/0xa0 > [ 2.697340] dump_stack+0x10/0x20 > [ 2.697342] __ubsan_handle_shift_out_of_bounds+0x1e3/0x390 > [ 2.697351] bh_get_inode_and_lblk_num.cold+0x12/0x94 > [ 2.697359] fscrypt_set_bio_crypt_ctx_bh+0x44/0x90 > [ 2.697365] submit_bh_wbc+0xb6/0x190 > [ 2.697370] block_read_full_folio+0x194/0x270 > [ 2.697371] ? __pfx_blkdev_get_block+0x10/0x10 > [ 2.697375] ? __pfx_blkdev_read_folio+0x10/0x10 > [ 2.697377] blkdev_read_folio+0x18/0x30 > [ 2.697379] filemap_read_folio+0x40/0xe0 > [ 2.697382] filemap_get_pages+0x5ef/0x7a0 > [ 2.697385] ? mmap_region+0x63/0xd0 > [ 2.697389] filemap_read+0x11d/0x520 > [ 2.697392] blkdev_read_iter+0x7c/0x180 > [ 2.697393] vfs_read+0x261/0x390 > [ 2.697397] ksys_read+0x71/0xf0 > [ 2.697398] __x64_sys_read+0x19/0x30 > [ 2.697399] x64_sys_call+0x1e88/0x26a0 > [ 2.697405] do_syscall_64+0x80/0x670 > [ 2.697410] ? __x64_sys_newfstat+0x15/0x20 > [ 2.697414] ? x64_sys_call+0x204a/0x26a0 > [ 2.697415] ? do_syscall_64+0xb8/0x670 > [ 2.697417] ? irqentry_exit_to_user_mode+0x2e/0x2a0 > [ 2.697420] ? irqentry_exit+0x43/0x50 > [ 2.697421] ? exc_page_fault+0x90/0x1b0 > [ 2.697422] entry_SYSCALL_64_after_hwframe+0x76/0x7e > [ 2.697425] RIP: 0033:0x75054cba4a06 > [ 2.697426] Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08 > [ 2.697427] RSP: 002b:00007fff973723a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 > [ 2.697430] RAX: ffffffffffffffda RBX: 00005ea9a2c02760 RCX: 000075054cba4a06 > [ 2.697432] RDX: 0000000000002000 RSI: 000075054c190000 RDI: 000000000000001b > [ 2.697433] RBP: 00007fff973723c0 R08: 0000000000000000 R09: 0000000000000000 > [ 2.697434] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 > [ 2.697434] R13: 00005ea9a2c027c0 R14: 00005ea9a2be5608 R15: 00005ea9a2be55f0 > [ 2.697436] > [ 2.697436] ---[ end trace ]--- > > This situation can happen for block devices because when > CONFIG_TRANSPARENT_HUGEPAGE is enabled, the maximum logical_block_size > is 64 KiB. set_init_blocksize() then sets the block device inode->i_blkbits > to 8 KiB, which is within this limit. > > File I/O does not trigger this problem because for filesystems that do not > support the FS_LBS feature, sb_set_blocksize() prevents sb->s_blocksize_bits > from being larger than PAGE_SHIFT. During inode allocation, > alloc_inode()->inode_init_always() assigns inode->i_blkbits from > sb->s_blocksize_bits. Currently, only xfs_fs_type has the FS_LBS flag, and > since xfs I/O paths do not reach submit_bh_wbc(), it does not hit the > left-shift underflow issue. > > Signed-off-by: Yongpeng Yang > --- > v2: > - Added more explanations about the issue in the commit message. > --- > fs/crypto/inline_crypt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c > index 5dee7c498bc8..6beb5f490612 100644 > --- a/fs/crypto/inline_crypt.c > +++ b/fs/crypto/inline_crypt.c > @@ -333,7 +333,7 @@ static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, > inode = mapping->host; > > *inode_ret = inode; > - *lblk_num_ret = ((u64)folio->index << (PAGE_SHIFT - inode->i_blkbits)) + > + *lblk_num_ret = (((u64)folio->index << PAGE_SHIFT) >> inode->i_blkbits) + > (bh_offset(bh) >> inode->i_blkbits); > return true; > } Applied to https://git.kernel.org/pub/scm/fs/fscrypt/linux.git/log/?h=for-current I also added: Fixes: 47dd67532303 ("block/bdev: lift block size restrictions to 64k") Cc: stable@vger.kernel.org - Eric