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 F0FF6241665; Fri, 13 Feb 2026 13:54:07 +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=1770990848; cv=none; b=aGr6YLzdDOz5WqvjYEPpD7XDO+cuFqtcYANU/dNp+jB4JKRxxEumClH5bWNksTn4NB+EstIrsqMEtZuUHfV1wJ5ANqLf/PkRxHz8lgdTg1D13rBwxt1wPfZROU/T1kL2ra0D4rRoFJJr2MmXT6W+nNS1EHNdLZkBbCHMFNnoRN4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770990848; c=relaxed/simple; bh=1bI950nj8yMLdXqzAL9/onlWZwG1UsaodzYo1LqufLE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PnsS8TlE20Ja0cQ47xZhQ32rJ1F1GfLBv5+aolDv9nMH7K83v/BCHdNZO1QjyqOjHVZOe2xxRS8x4nD95aAU4Jk5brMT5TsZUE1JLDDbE8PU8qzg4u/Ndj/cEX06z8d3TRRLHnDhzbkdNabGQ9Hj/JCaAJBkYB8p+Eea1lKlpB0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0BeWW1OB; 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="0BeWW1OB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 812F3C116C6; Fri, 13 Feb 2026 13:54:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770990847; bh=1bI950nj8yMLdXqzAL9/onlWZwG1UsaodzYo1LqufLE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0BeWW1OBE763ZHi3f98wO5Fj1G3Ubu81pUhdbAZcWragt6pRootLKlTRhMtjXDmjH 4F5WXykZdWvYa/aGmDogB+W/To4Qf8YAs6cfWizynS/Vrci70IKMCAg9qSQ3zmw3Py du1ObAeZ+2dnIkL0y+wDUrVfO6Hhb8cjzycnU2H0= 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 6.18 35/49] nilfs2: Fix potential block overflow that cause system hang Date: Fri, 13 Feb 2026 14:48:19 +0100 Message-ID: <20260213134710.160871395@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260213134708.885500854@linuxfoundation.org> References: <20260213134708.885500854@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-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 @@ -1093,6 +1093,9 @@ 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); @@ -1191,6 +1194,7 @@ 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; }