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 92A42226548; Thu, 17 Apr 2025 10:29:24 +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=1744885764; cv=none; b=mfVuvvqinWvP6ftXpSxT+ALuuscKodC8CLqn0byzJO59O3NE1lQiIR1FcXzodY9uX1TRd+N62tbKftN0MEw3UJB7b7Makt/oF5W7CzUrpJ1Jx3TJ4hhy0pRru6wa0e8WRhe1pXt/ByHn2Q9ga7YDcTZSCnuOHTFV6YmNvASp4Bg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744885764; c=relaxed/simple; bh=vj4JM7yLi/rS6Aqguv3WBwNNnEkfccwCEHy5GLTSbSo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=gPvwZnYZm7nOjB/kZxqtK3gW0cya6wX4Nb0GT8hCPnPaQ2O3kHL6yx7AEgaVEayAzg/ghTKGFTDS38PqEbLzt5ybrxImhFZzznZWF1hSdSTMLGmfItnJZ41xcwCD/IRqwqL0VAiqlAdGMbnzNnBzTsu/DhgPyD9Gxix4GGKmCzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IiiCCT+L; 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="IiiCCT+L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A6E3C4CEEA; Thu, 17 Apr 2025 10:29:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744885764; bh=vj4JM7yLi/rS6Aqguv3WBwNNnEkfccwCEHy5GLTSbSo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=IiiCCT+L3wl2v2qoff/qssuBn4HbA8hV5DqIHVmBqcFj5BCwlg52At6PwcGOOVxzr 8R2Yl8V42lZjYaDYj58zyVWo/zWnxWPNk4MAxuWxi1WJuuVxGeezRuk+c2X/v6y9Mr ZZWRxuh9QSNILH0d0M50uXBrbF/EEGJmrYfeZhGIrHthrpEyY01aGxmr82ei3rub+Z BRbbHQ98lvGWMLe7R1AGjytCPIvnQmnho3yYB4WR5Uf0VrvbEpURHTNSE5eE7jhsji uLmH/38hQzxB/RUbYxKvbbfIZqcjCfgXRPnHb0QNY0NWCSGJiw8iQ7nJKpp/KNDDjP +mgmlq+91m66w== Message-ID: <1c7aa66639d9297dae186181aa3a03ff237be81f.camel@kernel.org> Subject: Re: [PATCH] nfs: handle failure of nfs_get_lock_context in unlock path From: Jeff Layton To: Li Lingfeng , trondmy@kernel.org, anna@kernel.org, bcodding@redhat.com Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com Date: Thu, 17 Apr 2025 06:29:22 -0400 In-Reply-To: <20250417072508.3850532-1-lilingfeng3@huawei.com> References: <20250417072508.3850532-1-lilingfeng3@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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: >=20 > 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 f= 3 > 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 ]--- >=20 > Free the allocated nfs4_unlockdata when nfs_get_lock_context() fails and > return NULL to terminate subsequent rpc_run_task, preventing NULL pointer > dereference. >=20 > 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(-) >=20 > 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_unlockd= ata(struct file_lock *fl, > struct nfs4_unlockdata *p; > struct nfs4_state *state =3D lsp->ls_state; > struct inode *inode =3D state->inode; > + struct nfs_lock_context *l_ctx; > =20 > p =3D kzalloc(sizeof(*p), GFP_KERNEL); > if (p =3D=3D NULL) > return NULL; > + l_ctx =3D nfs_get_lock_context(ctx); > + if (!IS_ERR(l_ctx)) { > + p->l_ctx =3D l_ctx; > + } else { > + kfree(p); > + return NULL; > + } > p->arg.fh =3D NFS_FH(inode); > p->arg.fl =3D &p->fl; > p->arg.seqid =3D seqid; > @@ -7085,7 +7093,6 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdat= a(struct file_lock *fl, > p->lsp =3D lsp; > /* Ensure we don't close file until we're done freeing locks! */ > p->ctx =3D 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? > - p->l_ctx =3D nfs_get_lock_context(ctx); > locks_init_lock(&p->fl); > locks_copy_lock(&p->fl, fl); > p->server =3D NFS_SERVER(inode); Good catch: Reviewed-by: Jeff Layton