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 65E6937646D; Tue, 17 Feb 2026 20:44:28 +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=1771361068; cv=none; b=t1fcSNXnKItrjGr+nJ+7OugUOisN94rJkcoBxVm4gwWO4Yuk06lc7THcbxDFwep8ZBzsT7fg2oCluHOVfv1xkiUhKUkA+oS/fa1Gc75QyqbhaxAsOxHsm9PSkevMLTbflTS6CqnN0yt48RmFLsf0/50NO4QybfoSKq0nY1rQAVw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771361068; c=relaxed/simple; bh=vEfyLO9oVqGEvRbYYVQMHUuepnpvURq8gkDmykyad0c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oworlgBU9zy4sm5ls0IV/4sqngDrgrFiIL0vaMvibAFqcbg5wNWWDusnqZGqaw02UYd8SyfKeV2jiXCL79NIOx7LF0WSvqXojhp23SNspIu7RkIDUPY/rf+HcgZ0fRcs/7iKVsiNNNReBrnA74hYxjXtw1bsoacZGB16rANfvy8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CfOwooqB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CfOwooqB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB247C4CEF7; Tue, 17 Feb 2026 20:44:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771361068; bh=vEfyLO9oVqGEvRbYYVQMHUuepnpvURq8gkDmykyad0c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CfOwooqBOI2CZOKvV97KHwB4dkc2X+WjucvfRu+ZqOjkeE5Ly/nkpb+5sHsod1eyU Ae/+mW4I45eMUlv9DsjUta3jwyFEwQnaw7aNBU/COf4NkO2S7YVqmOVqpNXngecHFq HQNboojiMZP+Iytt5fXV8fgmU5ohNnHXzCfr/4Dw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+7eedce5eb281acd832f0@syzkaller.appspotmail.com, Edward Adam Davis , Ryusuke Konishi , Viacheslav Dubeyko Subject: [PATCH 5.15 04/39] nilfs2: Fix potential block overflow that cause system hang Date: Tue, 17 Feb 2026 21:31:13 +0100 Message-ID: <20260217200003.100149224@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260217200002.929083107@linuxfoundation.org> References: <20260217200002.929083107@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Edward Adam Davis commit ed527ef0c264e4bed6c7b2a158ddf516b17f5f66 upstream. When a user executes the FITRIM command, an underflow can occur when calculating nblocks if end_block is too small. Since nblocks is of type sector_t, which is u64, a negative nblocks value will become a very large positive integer. This ultimately leads to the block layer function __blkdev_issue_discard() taking an excessively long time to process the bio chain, and the ns_segctor_sem lock remains held for a long period. This prevents other tasks from acquiring the ns_segctor_sem lock, resulting in the hang reported by syzbot in [1]. If the ending block is too small, typically if it is smaller than 4KiB range, depending on the usage of the segment 0, it may be possible to attempt a discard request beyond the device size causing the hang. Exiting successfully and assign the discarded size (0 in this case) to range->len. Although the start and len values in the user input range are too small, a conservative strategy is adopted here to safely ignore them, which is equivalent to a no-op; it will not perform any trimming and will not throw an error. [1] task:segctord state:D stack:28968 pid:6093 tgid:6093 ppid:2 task_flags:0x200040 flags:0x00080000 Call Trace: rwbase_write_lock+0x3dd/0x750 kernel/locking/rwbase_rt.c:272 nilfs_transaction_lock+0x253/0x4c0 fs/nilfs2/segment.c:357 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2569 [inline] nilfs_segctor_thread+0x6ec/0xe00 fs/nilfs2/segment.c:2684 [ryusuke: corrected part of the commit message about the consequences] Fixes: 82e11e857be3 ("nilfs2: add nilfs_sufile_trim_fs to trim clean segs") Reported-by: syzbot+7eedce5eb281acd832f0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7eedce5eb281acd832f0 Signed-off-by: Edward Adam Davis Signed-off-by: Ryusuke Konishi Cc: stable@vger.kernel.org Signed-off-by: Viacheslav Dubeyko Signed-off-by: Greg Kroah-Hartman --- fs/nilfs2/sufile.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/nilfs2/sufile.c +++ b/fs/nilfs2/sufile.c @@ -1091,6 +1091,9 @@ int nilfs_sufile_trim_fs(struct inode *s else end_block = start_block + len - 1; + if (end_block < nilfs->ns_first_data_block) + goto out; + segnum = nilfs_get_segnum_of_block(nilfs, start_block); segnum_end = nilfs_get_segnum_of_block(nilfs, end_block); @@ -1188,6 +1191,7 @@ int nilfs_sufile_trim_fs(struct inode *s out_sem: up_read(&NILFS_MDT(sufile)->mi_sem); +out: range->len = ndiscarded << nilfs->ns_blocksize_bits; return ret; }