| Message ID | 20240214140110.606171-1-aiswarya.cyriac@opensynergy.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v3] ALSA: virtio: Fix "Coverity: virtsnd_kctl_tlv_op(): Uninitialized variables" warning. | expand |
>>On Wed, Feb 14, 2024 at 03:01:10PM +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 <anton.yakovlev@opensynergy.com> >> Signed-off-by: Aiswarya Cyriac <aiswarya.cyriac@opensynergy.com> >> Reported-by: coverity-bot <keescook+coverity-bot@chromium.org> >> Addresses-Coverity-ID: 1583619 ("Uninitialized variables") >> Fixes: d6568e3de42d ("ALSA: virtio: add support for audio controls") >> --- >> sound/virtio/virtio_kctl.c | 25 +++++++++++++++++++++---- >> 1 file changed, 21 insertions(+), 4 deletions(-) >> >> diff --git a/sound/virtio/virtio_kctl.c b/sound/virtio/virtio_kctl.c >> index 0c6ac74aca1e..40606eb381af 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_cleanup; >> } >> >> sg_init_one(&sg, tlv, size); >> @@ -266,6 +266,11 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag, >> case SNDRV_CTL_TLV_OP_READ: >> hdr->hdr.code = cpu_to_le32(VIRTIO_SND_R_CTL_TLV_READ); >> >> + /* Since virtsnd_ctl_msg_send() drops the reference, we increase >> + * the counter to be consistent with the on_cleanup path. >> + */ > This is not how multi-line comments should look. > Adding overhead here is just a waste of cycles. > Instead, separate error handling and normal exit paths. > Then you will not need to increase the refcount here. Ok. >> + virtsnd_ctl_msg_ref(msg); >> + >> rc = virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false); >> if (!rc) { >> if (copy_to_user(utlv, tlv, size)) >> @@ -281,14 +286,26 @@ 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 >> + } else { >> + /* Same as the comment above */ > Same thing. > Besides, this kind of cross referencing breaks immediately when > someone adds a comment in the middle. I agree. I will update the patch >> + virtsnd_ctl_msg_ref(msg); >> + >> 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); >> >> break; >> } >> >> +on_cleanup: >> + virtsnd_ctl_msg_unref(msg); >> + >> kfree(tlv); >> >> return rc; > on_cleanup is not informative, coding style says: > "Choose label names which say what the goto does or why the goto > exists." > And saving on duplication here by paying elsewhere does not make sense. > So you do this instead: > kfree(tlv); > return rc; > on_error: > virtsnd_ctl_msg_unref(msg); > kfree(tlv); > return rc; > This is very ideomatic. Thanks. I will separate error and non error cases and update patch Thanks, Aiswarya Cyriac Software Engineer OpenSynergy GmbH Rotherstr. 20, 10245 Berlin EMail: aiswarya.cyriac@opensynergy.com www.opensynergy.com Handelsregister/Commercial Registry: Amtsgericht Charlottenburg, HRB 108616B Geschäftsführer/Managing Director: Régis Adjamah
diff --git a/sound/virtio/virtio_kctl.c b/sound/virtio/virtio_kctl.c index 0c6ac74aca1e..40606eb381af 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_cleanup; } sg_init_one(&sg, tlv, size); @@ -266,6 +266,11 @@ static int virtsnd_kctl_tlv_op(struct snd_kcontrol *kcontrol, int op_flag, case SNDRV_CTL_TLV_OP_READ: hdr->hdr.code = cpu_to_le32(VIRTIO_SND_R_CTL_TLV_READ); + /* Since virtsnd_ctl_msg_send() drops the reference, we increase + * the counter to be consistent with the on_cleanup path. + */ + virtsnd_ctl_msg_ref(msg); + rc = virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false); if (!rc) { if (copy_to_user(utlv, tlv, size)) @@ -281,14 +286,26 @@ 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 + } else { + /* Same as the comment above */ + virtsnd_ctl_msg_ref(msg); + rc = virtsnd_ctl_msg_send(snd, msg, &sg, NULL, false); + } + + break; + default: + rc = -EINVAL; + WARN_ON(1); break; } +on_cleanup: + virtsnd_ctl_msg_unref(msg); + kfree(tlv); return rc;