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Thu, 4 Jun 2026 15:25:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id lGq7MtaYIWoJJgAAD6G6ig (envelope-from ); Thu, 04 Jun 2026 15:25:10 +0000 Date: Thu, 04 Jun 2026 17:25:10 +0200 Message-ID: <87v7byuy3t.wl-tiwai@suse.de> From: Takashi Iwai To: Ji'an Zhou Cc: linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, tiwai@suse.de Subject: Re: [PATCH] ALSA: PCM: Fix wait queue list corruption in snd_pcm_drain() on linked streams In-Reply-To: <20260604142559.3840881-1-eilaimemedsnaimel@gmail.com> References: <20260604142559.3840881-1-eilaimemedsnaimel@gmail.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org 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 X-Spam-Flag: NO X-Rspamd-Action: no action X-Spam-Level: X-Spamd-Result: default: False [-3.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FREEMAIL_TO(0.00)[gmail.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_THREE(0.00)[4]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:mid,suse.de:dkim] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 017F47583F X-Spam-Score: -3.51 On Thu, 04 Jun 2026 16:25:59 +0200, Ji'an Zhou wrote: > > snd_pcm_drain() uses init_waitqueue_entry which does not clear > entry.prev/next, and add_wait_queue with a conditional > remove_wait_queue that is skipped when to_check is no longer > in the group after concurrent UNLINK. The orphaned wait entry > remains on the unlinked substream sleep queue. On the next > drain iteration, add_wait_queue adds the entry to a new queue > while still linked on the old one, corrupting both lists. A > subsequent wake_up dereferences NULL at the func pointer > (mapped from the spinlock at offset 0 of the misinterpreted > wait_queue_head_t), causing a kernel panic. > > Replace init_waitqueue_entry/add_wait_queue/conditional > remove_wait_queue with init_wait_entry/prepare_to_wait/ > finish_wait. init_wait_entry clears prev/next via > INIT_LIST_HEAD on each iteration and sets > autoremove_wake_function which auto-removes the entry on > wake-up. finish_wait safely handles both the already-removed > and still-queued cases. > > Fixes: 9b1dbd69ba6f ("ALSA: pcm: fix use-after-free on linked stream runtime in snd_pcm_drain") > Signed-off-by: Ji'an Zhou Applied now. Thanks. Takashi