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 48C462940D; Wed, 5 Nov 2025 00:38:31 +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=1762303113; cv=none; b=t+GXxjKTELhEfdmyQvCSEmVwD3AYhAOVWEDLpkMkTGeRweLrGYAFYyFXbDzLHzpUGzKU9ethbXCXFI7Qcdle4lwkyS9rfOAcH85oBdLfZ3rtigttmRyT5XJuXBmMs10p1eWqWb9j/o4e7at57N4NCnAVC7PXhltx7Z36BZJp+nY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762303113; c=relaxed/simple; bh=ozzedGexVm3c7LAJROJn2IsFXaRUObyKrN+iT0hZtCY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=cKw4tcby5VQKjP8Yd7QMloQ0ek0pVnhtT80m/VSsUoWik4716bFgo4Mo5K8LZFWGl92kLGH03607MHC8ZgK/9f13cccBvMFPNJDiwLs3M0QDHmaunha6QMsEcQIDa7qRLPZ20E773j3WoivWKyNITu8B0tCbKTUA13CqPXZjQMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ptR0KmoB; 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="ptR0KmoB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C518C4CEF7; Wed, 5 Nov 2025 00:38:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762303111; bh=ozzedGexVm3c7LAJROJn2IsFXaRUObyKrN+iT0hZtCY=; h=From:To:Cc:Subject:Date:From; b=ptR0KmoBFtTbL19XkNIzXueSZWZY/twdtmdgLFHw75tnPtDRLgthL4Nu42I1+NGgP R9YGZwqNNroue9gVRuJOYNFQl8c5CCpwsAb/DUR/WcDNILYwgUPd8NYjGCpxlA4LP2 1NoLoMvXzsIiAz/i4dwPKYEtJgwki5bEAnh5aniham5fCcjSgmCJtmVRQBVaQ7GIgk Lh70Vw9Elxqxq8hv8mLW+41TPihRhOeqYz4Fmh1g1DHOdWO0n3htihIMSlbC5J+DKF wBNG2RzCxDahK8tEKZinOcULkU3G+14Y2GCKiuCRrqWtYNCm9USN72qyt2RU76j0Qv uA1GHnu4H3/xQ== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, Luis Chamberlain , Yongpeng Yang , stable@vger.kernel.org, Eric Biggers Subject: [PATCH v3] fscrypt: fix left shift underflow when inode->i_blkbits > PAGE_SHIFT Date: Tue, 4 Nov 2025 16:36:42 -0800 Message-ID: <20251105003642.42796-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.51.2 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yongpeng Yang When simulating an nvme device on qemu with both logical_block_size and physical_block_size set to 8 KiB, an 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 13, 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 Fixes: 47dd67532303 ("block/bdev: lift block size restrictions to 64k") Cc: stable@vger.kernel.org [EB: use folio_pos() and consolidate the two shifts by i_blkbits] Signed-off-by: Eric Biggers --- This patch is targeting the fscrypt/for-current tree fs/crypto/inline_crypt.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c index 5dee7c498bc8..ed6e926226b5 100644 --- a/fs/crypto/inline_crypt.c +++ b/fs/crypto/inline_crypt.c @@ -331,12 +331,11 @@ static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh, if (!mapping) return false; inode = mapping->host; *inode_ret = inode; - *lblk_num_ret = ((u64)folio->index << (PAGE_SHIFT - inode->i_blkbits)) + - (bh_offset(bh) >> inode->i_blkbits); + *lblk_num_ret = (folio_pos(folio) + bh_offset(bh)) >> inode->i_blkbits; return true; } /** * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline base-commit: 6146a0f1dfae5d37442a9ddcba012add260bceb0 -- 2.51.2