From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793907345; b=5hHMucWssVAYVNV6zALyjnTRRj8/HAO18owKDXF2KrRBloiSMs9UcvT8oPlSKN9c2R0a ONBatJepbmmc8SKUWGuzPnL45halhZYg12Fe2YW79xEqBF63CC6iPPYIDPS+R1XSAgiGp Zl8SjpYpGjv+v3qR+0Tsc+6U49W8dJslmV55qYyMAmfCcd78+RfozWNv5yVnRdnzv2vrz yGYlNa3MdcBo+ALrw0KEz+8j0g1/kjXjLE53nsUO07gaaNlbf1Aexr67EtPtzLL8wXBur gikiUEzwdbMO69W3aV4G6kIC8TtEeUwZz52LhtxGI6gbqnE3uSrKIRdjbcqe+f3UqpQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793907345; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=alsXUfuEo/F1zePFVRl45Ndme/OflhiQcp41SPItDb0=; b=Ey6hVcbp7BFwAOJhn4jNKvkoWI7Afq+2zwIzIXpIi/alSUo1mMj9e/L5/b8ULBw4tffS lLUQQ2DUqqAwmFI0I/ZwgVdvk3L1elzAKyXYfBDHyrrXqXvrG6mAYTObxp5iYmf9nLyLg 6j7Hrlz45Ny3qsZmph9z3WhAWbb8hJTXAy1rwzWFIl4dB/PR/68ciaOhPWrpMmrITkUit wa74kjP8b+QKSXrzJvFcpq21RUMUy5aulG43zDpxG1WTtZxlUJm2e4DWHfhbqOVkObdH2 xFAD0YvIfryO22v3JZqQM/akIUVxvMlYd+nhsjiRV/kJJ0KL3BspzH9+1W18lKqt38A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="dW/11WUL"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2365B6077B6B; Thu, 5 Nov 2026 19:35:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dW/11WUL Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6CEB1F0089E; Thu, 5 Nov 2026 19:35:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793907343; bh=alsXUfuEo/F1zePFVRl45Ndme/OflhiQcp41SPItDb0=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=dW/11WULePWBsogqlKJCGC7JYPbCbnYXRV+C/X7JOVxLXj5zOAba52zQpFTgNc3SU VqxLxyGyN/7wF0BTtfNixYDyxmB3E86QX9Ux9RGZ1zXR/EzZ2ZJyrhkPfunyxJJIZl un+xpBbQSiFaF0jJ6u/VW8rXe40ajptsRa6PjrbVxC7gTAonFrr3x4gk/kvpjOE5P1 HarizfUM9JcPoR6EP40r+AaFcc6yhKBRuZw/KiwaBzFcWGsYWpC0CK/E6jNjHZpgDM EXhNA7+mREaW+iD5ECYOta1cjbh7H74x/1uUayMthsMGSyY9SbGLuxXinygzr+5A4r a3NkeRuyCBiAg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RESEND v2 14/23] proc: let procfs copy in writes before pinning the entry Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" Cc: "Linus Torvalds" , "Jann Horn" , "Josef Bacik" , "Chris Mason" , "Jeff Layton" , NeilBrown , "Eric Dumazet" , "Thomas Gleixner" , "Al Viro" , "Jonathan Corbet" , "Christoph Hellwig" , "Greg Kroah-Hartman" , "Joel Granados" , "Kees Cook" , "Jan Kara" , "Jan Kara" , linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-serial@vger.kernel.org, "Takashi Iwai" , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, "Chuck Lever" , tytso@mit.edu, dmitry.torokhov@gmail.com, "Petr Pavlu" , "Anna Schumaker" , yukuai@fygo.io, "Heiko Carstens" , "Vasily Gorbik" , "Alexander Gordeev" , "Christian Borntraeger" In-Reply-To: <20261104-work-procfs-core-v2-14-76ace653a773@kernel.org> References: <20261104-work-procfs-core-v2-0-76ace653a773@kernel.org> <20261104-work-procfs-core-v2-14-76ace653a773@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 05 Nov 2026 19:35:41 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Low] proc: split __free(kvfree) declaration and initialization in pde_wr= ite_buf() -- commit e52627c4b4d80d32822781f143a8c1245bd64a2c Author: Christian Brauner proc: let procfs copy in writes before pinning the entry This commit introduces a ->proc_write_buf() callback in struct proc_ops so that procfs can copy write data from userspace into a NUL-terminated kernel buffer before pinning the proc_dir_entry. This prevents userspace page faults during write copies from blocking remove_proc_entry(). > diff --git a/fs/proc/inode.c b/fs/proc/inode.c > index d51ab7548b117..df1caa0f238df 100644 > --- a/fs/proc/inode.c > +++ b/fs/proc/inode.c > @@ -417,11 +417,44 @@ static ssize_t pde_write(struct proc_dir_entry *pde= , struct file *file, const ch > return -EIO; > } > =20 > +/* > + * procfs copies in what is written before it pins the entry. A writer t= hat > + * faults on its buffer then doesn't hold up remove_proc_entry(). > + */ > +static ssize_t pde_write_buf(struct proc_dir_entry *pde, struct file *fi= le, > + const char __user *ubuf, size_t count, loff_t *ppos) > +{ > + char *buf __free(kvfree) =3D NULL; > + size_t size; > + ssize_t rv; > + > + size =3D pde->write_size; > + if (count > size) { > + if (!pde_has_short_writes(pde)) > + return -EINVAL; > + count =3D size; > + } > + buf =3D kvmalloc(count + 1, GFP_KERNEL); [Severity: Low] As reported by Sashiko on RFC [1], this isn't a bug, but in pde_write_buf() (called from proc_reg_write()), buf is declared with __free(kvfree) =3D NULL at the top of the function and assigned later with kvmalloc() after the count > size check. Per the Cleanup API conventions in include/linux/cleanup.h, should buf be defined and initialized in a single statement at the allocation site: char *buf __free(kvfree) =3D kvmalloc(count + 1, GFP_KERNEL); after validating count? [1] https://lore.kernel.org/r/sashiko-outbox-195538@kernel.org --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261104-work-procf= s-core-v2-0-76ace653a773@kernel.org?part=3D14