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bh=DX6t6X+yIdGbLB39W9vftzQkoVtLDPdmu/GnvJ6LhTI=; b=t+ekt5pViC8fLjh59BuatpPUvUykK4qjQ+oVpsii7Ccrw3HxrO2k2JpGJW0Dqe16BIBx35 WfYno0nra2hbuaAg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 9972F13A39; Fri, 16 Feb 2024 14:02:03 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap1.dmz-prg2.suse.org with ESMTPSA id k1L1I9tqz2VdLgAAD6G6ig (envelope-from ); Fri, 16 Feb 2024 14:02:03 +0000 Date: Fri, 16 Feb 2024 15:02:03 +0100 Message-ID: <87a5o0ik2s.wl-tiwai@suse.de> From: Takashi Iwai To: "Michael S. Tsirkin" Cc: Aiswarya Cyriac , jasowang@redhat.com, perex@perex.cz, tiwai@suse.com, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, Anton Yakovlev , coverity-bot Subject: Re: [v4 PATCH] ALSA: virtio: Fix "Coverity: virtsnd_kctl_tlv_op(): Uninitialized variables" warning. In-Reply-To: <20240216084610-mutt-send-email-mst@kernel.org> References: <20240216100643.688590-1-aiswarya.cyriac@opensynergy.com> <20240216062630-mutt-send-email-mst@kernel.org> <87eddcikz6.wl-tiwai@suse.de> <20240216084610-mutt-send-email-mst@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=LxvnyCHL; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=t+ekt5pV X-Spamd-Result: default: False [-0.81 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; TAGGED_RCPT(0.00)[coverity-bot]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[11]; MID_CONTAINS_FROM(1.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: 001B0220B0 X-Spamd-Bar: / On Fri, 16 Feb 2024 14:48:10 +0100, Michael S. Tsirkin wrote: > > On Fri, Feb 16, 2024 at 02:42:37PM +0100, Takashi Iwai wrote: > > On Fri, 16 Feb 2024 12:27:48 +0100, > > Michael S. Tsirkin wrote: > > > > > > On Fri, Feb 16, 2024 at 11:06:43AM +0100, Aiswarya Cyriac wrote: > > > > This commit fixes the following warning when building virtio_snd driver. > > > > > > > > " > > > > *** CID 1583619: Uninitialized variables (UNINIT) > > > > sound/virtio/virtio_kctl.c:294 in virtsnd_kctl_tlv_op() > > > > 288 > > > > 289 break; > > > > 290 } > > > > 291 > > > > 292 kfree(tlv); > > > > 293 > > > > vvv CID 1583619: Uninitialized variables (UNINIT) > > > > vvv Using uninitialized value "rc". > > > > 294 return rc; > > > > 295 } > > > > 296 > > > > 297 /** > > > > 298 * virtsnd_kctl_get_enum_items() - Query items for the ENUMERATED element type. > > > > 299 * @snd: VirtIO sound device. > > > > " > > > > > > > > This warning is caused by the absence of the "default" branch in the > > > > switch-block, and is a false positive because the kernel calls > > > > virtsnd_kctl_tlv_op() only with values for op_flag processed in > > > > this block. > > > > > > > > Also, this commit unifies the cleanup path for all possible control > > > > paths in the callback function. > > > > > > > > Signed-off-by: Anton Yakovlev > > > > Signed-off-by: Aiswarya Cyriac > > > > Reported-by: coverity-bot > > > > Addresses-Coverity-ID: 1583619 ("Uninitialized variables") > > > > Fixes: d6568e3de42d ("ALSA: virtio: add support for audio controls") > > > > > > > > > > > > > --- > > > > sound/virtio/virtio_kctl.c | 19 +++++++++++++++---- > > > > 1 file changed, 15 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/sound/virtio/virtio_kctl.c b/sound/virtio/virtio_kctl.c > > > > index 0c6ac74aca1e..7aa79c05b464 100644 > > > > --- a/sound/virtio/virtio_kctl.c > > > > +++ b/sound/virtio/virtio_kctl.c > > > > @@ -253,8 +253,8 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag, > > > > > > > > tlv = kzalloc(size, GFP_KERNEL); > > > > if (!tlv) { > > > > - virtsnd_ctl_msg_unref(msg); > > > > - return -ENOMEM; > > > > + rc = -ENOMEM; > > > > + goto on_msg_unref; > > > > } > > > > > > > > sg_init_one(&sg, tlv, size); > > > > @@ -281,14 +281,25 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag, > > > > hdr->hdr.code = > > > > cpu_to_le32(VIRTIO_SND_R_CTL_TLV_COMMAND); > > > > > > > > - if (copy_from_user(tlv, utlv, size)) > > > > + if (copy_from_user(tlv, utlv, size)) { > > > > rc = -EFAULT; > > > > - else > > > > + goto on_msg_unref; > > > > + } else { > > > > rc = virtsnd_ctl_msg_send(snd, msg, &sg, NULL, false); > > > > + } > > > > > > > > break; > > > > + default: > > > > + rc = -EINVAL; > > > > + /* We never get here - we listed all values for op_flag */ > > > > + WARN_ON(1); > > > > + goto on_msg_unref; > > > > } > > > > + kfree(tlv); > > > > + return rc; > > > > > > > > +on_msg_unref: > > > > + virtsnd_ctl_msg_unref(msg); > > > > kfree(tlv); > > > > > > > > return rc; > > > > > > I don't really like adding code for a false-positive but ALSA > > > maintainers seem to like this. If yes, this seems like as good > > > a way as any to do it. > > > > Err, no, you misunderstood the situation. > > > > I took the v1 patch quickly because: > > - It was with Anton's SOB, who is another maintainer of the driver > > - I assumed you lost interest in this driver since you haven't reacted > > to the previous patches for long time > > - The change there was small and simple enough > > > > Now, it grows unnecessarily large, and yet you complained. Why should > > I take it, then? > > > > This is a subtle cosmetic issue that isn't worth for wasting too much > > time and energy. If we want to shut up the compile warning, and this > > is a case where it can't happen, just put the "default:" to the > > existing case. If you want to be user-friendly, put some comment. > > That's all. It'll be a one-liner. > > > > OTOH, if we do care and want to catch any potential logical mistake, > > you can put WARN(). But, this doesn't have to go out as an error. > > Simply putting WARN() for the default and going through would work, > > too. > > > > Or we can keep this lengthy changes if we want, too. > > > > So, I really don't mind which way to fix as long as it works correctly > > (and doesn't look too ugly). Please make agreement among you guys, > > and resubmit if needed. > > > > > > thanks, > > > > Takashi > > OK sorry about too verbose. I mean since Anton wants it, I ack this. > > Acked-by: Michael S. Tsirkin Alright, I applied this one. Thanks! Takashi