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 525DB35FF61; Fri, 13 Feb 2026 13:55:09 +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=1770990909; cv=none; b=rp3DhDnpYAVZ0lid/FHvcKVmrn5FBR0T1aoXSKZiD8x1PDiqUmRO+qaDxZJBAOP1NZbxgY1bggiVqTRix1y9Iwg5o+IdEUiSeuxFwV1YSP57V/gMjwLEna79yLOkSsOEtb6fVT+Ru/dlY4yunomqeA3qGKvD9bQr3WZXxsFU53c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770990909; c=relaxed/simple; bh=/+ZBDWpQIsCzuzi3RGGcL5spJWbOHIhekl3k7ENqgy8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sbpjP3VsSm6wIASm2SyCQM9FqMMQFsJ4XkgeLUpjflbuDkk5wB2fDQLIcIWabDZoLk/ZRLFiz1MLPpPe2xMNP/XPr0/NkCnfYBHsd1E43jlk573Y17UjHBgSjfxHJc9JJqlG8Llzk+UFYCayELf502UCpsQqD6nm9eGRtURmSPk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vDkFzRq4; 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="vDkFzRq4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3C10C116C6; Fri, 13 Feb 2026 13:55:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770990909; bh=/+ZBDWpQIsCzuzi3RGGcL5spJWbOHIhekl3k7ENqgy8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vDkFzRq4/949/IES4h4lCRrtyQDRO7J73nGu3Dp6LuPKcOtQlVBPUL6eiukpnKBeT XDr83NdCkPEvg8m5aYOhJpN+Y2jHQgV/qc1ZmSV29fN+lBzLZ/w5o9kpgVb/tXpIPv T5hNNyDncUQ76g50Pd6n8oPZtkzcNhMVkt8RXfuM= 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 6.12 11/24] nilfs2: Fix potential block overflow that cause system hang Date: Fri, 13 Feb 2026 14:48:30 +0100 Message-ID: <20260213134705.141008653@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260213134704.728003077@linuxfoundation.org> References: <20260213134704.728003077@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 6.12-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 @@ -1106,6 +1106,9 @@ 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); @@ -1203,6 +1206,7 @@ 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; }