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 2761028C867; Tue, 13 May 2025 12:24:35 +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=1747139076; cv=none; b=IbNpmsYOnFjcFeDv173opSFl1/C441hqk9nfl7k3u86Y/nfkumjot8juVyjUU+Jcf2f0xGAjWgDZVerzMEONqxOFRF4TSvMl89O1uwabJtjoCiLJ1dzteiDTA46K5+IuXgnzsUvNC+DkE8RusLpe8k1cUP4cd27l3HNU6FkJoGE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747139076; c=relaxed/simple; bh=Zwh3UW17Zhi7QJAi/pBZJjlRLlp+qGCk6fggOwaejA0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=nwZWOOeRj64d9wTXJQp75bmL+a6L9UtCVaX7y0rRQBibJgYu+r3pyn3w5CuNid0P58FMVp42UsH7yf1CTYPStsT6Dg8Mq1P3c/3XiiKsRC6dFJxfBPTkuF8P5ephpchybzIa84w2/L/s+DboWiLAS6UuDMU7E+4tjoaqF0FZiM8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P6UKUC9D; 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="P6UKUC9D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBF28C4CEE4; Tue, 13 May 2025 12:24:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747139075; bh=Zwh3UW17Zhi7QJAi/pBZJjlRLlp+qGCk6fggOwaejA0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=P6UKUC9DpBvjuKBG83RLwv8KNkNfgDbVE7oFwsnQh7E5ABYtIIbeX1SMhT/zXmT/N mv9BSsdC1/miANvq+21khLTSMezlkd7OT4R1IadeOJOx6AxcRWMITOSe2/KPgSYuC8 6yitmfwF2ckaYpe2L4Dbh/oz5bwCvNNKbKuiIdzyGQoKWXIhyjBZvukUeuTvZvN/4l YyaB6jNA1YzeZNKpiatISLbJqq+ZbTx32VH4/JdKBQ+d/MN08CR4eaqnlcIjUk+soV CLREHO/dayiv7lGF2NzCyNdyhoMDWYMs9MMK9xPargoFZUa0h2O60MEJIfRSyLh0VN rQcsB62T9ilAg== Message-ID: Subject: Re: [PATCH v2] 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: Tue, 13 May 2025 07:24:32 -0500 In-Reply-To: <20250513074226.3362070-1-lilingfeng3@huawei.com> References: <20250513074226.3362070-1-lilingfeng3@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Tue, 2025-05-13 at 15:42 +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") > Link: https://lore.kernel.org/all/21817f2c-2971-4568-9ae4-1ccc25f7f1ef@hu= awei.com/ > Signed-off-by: Li Lingfeng > --- > Changes in v2: > Add a comment explaining that error handling for ctx acquisition failur= e > is unnecessary. >=20 > fs/nfs/nfs4proc.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) >=20 > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index 970f28dbf253..e52e2ac1ab39 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -7074,18 +7074,29 @@ 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; > p->res.seqid =3D seqid; > p->lsp =3D lsp; > /* Ensure we don't close file until we're done freeing locks! */ > + /* > + * Since the caller holds a reference to ctx, the refcount must be non-= zero. > + * Therefore, error handling for failed ctx acquisition is unnecessary = here. > + */ > p->ctx =3D get_nfs_open_context(ctx); > - 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); Reviewed-by: Jeff Layton