From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (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 B69F3243953; Thu, 17 Apr 2025 12:24:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744892666; cv=none; b=s7ld89BQU51jqFWBQWY/uG0DLBVRescWL721IA6zbkcfXw18EAogJtxuBaRPs33xIoFl1KCFxj8d+0CgVbbouegH7CPnFfL4wRCSM//5CNY0iiIwyNEKsHFvu1vKtiI823lSAyssa0kX0DwmKZo2wXzWZN/eqA4e6qjkX05Lirg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744892666; c=relaxed/simple; bh=1DlkWNRVVOWBtp4cHwdycVCUOrGc+WAOGwTUMMCKqlg=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=iTl3doSR0SVSGFco/ayoh8KW/7Wj9KrOBLnj5Ig4hkNqiaLEM2bhwkfciCQ4kLcMFEoH/RxDQyhDadcXejCbPFCpCar52VqDsFpQ24lp/8IRApCNlLIg5H4NhQfBcVT6wXCWJZhk2cOpW//Au7jxlGIze2sZCn9a+BOkAazMu+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.234]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4ZdcS46mSWz2Cccp; Thu, 17 Apr 2025 20:20:52 +0800 (CST) Received: from kwepemg500017.china.huawei.com (unknown [7.202.181.81]) by mail.maildlp.com (Postfix) with ESMTPS id ABB541402C4; Thu, 17 Apr 2025 20:24:19 +0800 (CST) Received: from [10.174.179.155] (10.174.179.155) by kwepemg500017.china.huawei.com (7.202.181.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 17 Apr 2025 20:24:18 +0800 Message-ID: <678aae33-3af0-4229-a2ce-d9cef1572f96@huawei.com> Date: Thu, 17 Apr 2025 20:24:18 +0800 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH] nfs: handle failure of nfs_get_lock_context in unlock path To: Jeff Layton , , , CC: , , , , , , References: <20250417072508.3850532-1-lilingfeng3@huawei.com> <1c7aa66639d9297dae186181aa3a03ff237be81f.camel@kernel.org> From: Li Lingfeng In-Reply-To: <1c7aa66639d9297dae186181aa3a03ff237be81f.camel@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemg500017.china.huawei.com (7.202.181.81) 在 2025/4/17 18:29, Jeff Layton 写道: > On Thu, 2025-04-17 at 15:25 +0800, Li Lingfeng wrote: >> When memory is insufficient, the allocation of nfs_lock_context in >> nfs_get_lock_context() fails and returns -ENOMEM. If we mistakenly treat >> an nfs4_unlockdata structure (whose l_ctx member has been set to -ENOMEM) >> as valid and proceed to execute rpc_run_task(), this will trigger a NULL >> pointer dereference in nfs4_locku_prepare. For example: >> >> BUG: kernel NULL pointer dereference, address: 000000000000000c >> PGD 0 P4D 0 >> Oops: Oops: 0000 [#1] SMP PTI >> CPU: 15 UID: 0 PID: 12 Comm: kworker/u64:0 Not tainted 6.15.0-rc2-dirty #60 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 >> Workqueue: rpciod rpc_async_schedule >> RIP: 0010:nfs4_locku_prepare+0x35/0xc2 >> Code: 89 f2 48 89 fd 48 c7 c7 68 69 ef b5 53 48 8b 8e 90 00 00 00 48 89 f3 >> RSP: 0018:ffffbbafc006bdb8 EFLAGS: 00010246 >> RAX: 000000000000004b RBX: ffff9b964fc1fa00 RCX: 0000000000000000 >> RDX: 0000000000000000 RSI: fffffffffffffff4 RDI: ffff9ba53fddbf40 >> RBP: ffff9ba539934000 R08: 0000000000000000 R09: ffffbbafc006bc38 >> R10: ffffffffb6b689c8 R11: 0000000000000003 R12: ffff9ba539934030 >> R13: 0000000000000001 R14: 0000000004248060 R15: ffffffffb56d1c30 >> FS: 0000000000000000(0000) GS:ffff9ba5881f0000(0000) knlGS:00000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000000000000000c CR3: 000000093f244000 CR4: 00000000000006f0 >> Call Trace: >> >> __rpc_execute+0xbc/0x480 >> rpc_async_schedule+0x2f/0x40 >> process_one_work+0x232/0x5d0 >> worker_thread+0x1da/0x3d0 >> ? __pfx_worker_thread+0x10/0x10 >> kthread+0x10d/0x240 >> ? __pfx_kthread+0x10/0x10 >> ret_from_fork+0x34/0x50 >> ? __pfx_kthread+0x10/0x10 >> ret_from_fork_asm+0x1a/0x30 >> >> Modules linked in: >> CR2: 000000000000000c >> ---[ end trace 0000000000000000 ]--- >> >> Free the allocated nfs4_unlockdata when nfs_get_lock_context() fails and >> return NULL to terminate subsequent rpc_run_task, preventing NULL pointer >> dereference. >> >> Fixes: f30cb757f680 ("NFS: Always wait for I/O completion before unlock") >> Signed-off-by: Li Lingfeng >> --- >> fs/nfs/nfs4proc.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c >> index 970f28dbf253..9f5689c43a50 100644 >> --- a/fs/nfs/nfs4proc.c >> +++ b/fs/nfs/nfs4proc.c >> @@ -7074,10 +7074,18 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, >> struct nfs4_unlockdata *p; >> struct nfs4_state *state = lsp->ls_state; >> struct inode *inode = state->inode; >> + struct nfs_lock_context *l_ctx; >> >> p = kzalloc(sizeof(*p), GFP_KERNEL); >> if (p == NULL) >> return NULL; >> + l_ctx = nfs_get_lock_context(ctx); >> + if (!IS_ERR(l_ctx)) { >> + p->l_ctx = l_ctx; >> + } else { >> + kfree(p); >> + return NULL; >> + } >> p->arg.fh = NFS_FH(inode); >> p->arg.fl = &p->fl; >> p->arg.seqid = seqid; >> @@ -7085,7 +7093,6 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, >> p->lsp = lsp; >> /* Ensure we don't close file until we're done freeing locks! */ >> p->ctx = get_nfs_open_context(ctx); > Not exactly the same problem, but get_nfs_open_context() can fail too. > Does it need error handling for that as well? Hi, IIUC, nfs_open_context is allocated during file open and attached to filp->private_data. Upon successful file opening, the context remains valid. Post-lock acquisition, nfs_open_context can be retrieved via file_lock->file->nfs_open_context chain. Thus get_nfs_open_context() here should have non-failure guarantee in standard code paths. Best regards, Lingfeng > >> - p->l_ctx = nfs_get_lock_context(ctx); >> locks_init_lock(&p->fl); >> locks_copy_lock(&p->fl, fl); >> p->server = NFS_SERVER(inode); > Good catch: > > Reviewed-by: Jeff Layton >