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Wed, 7 Oct 2026 14:04:49 +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 SBGiGYFRxmq3MgAAD6G6ig (envelope-from ); Wed, 07 Oct 2026 14:04:49 +0000 Date: Wed, 07 Oct 2026 16:04:49 +0200 Message-ID: <878q49obcu.wl-tiwai@suse.de> From: Takashi Iwai To: Peter Ujfalusi Cc: vkoul@kernel.org, perex@perex.cz, tiwai@suse.com, pierre-louis.bossart@linux.dev, linux-sound@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/4] ALSA: compress: fix buffer leak on repeated SET_PARAMS In-Reply-To: <20261007132509.18237-2-peter.ujfalusi@linux.intel.com> References: <20261007132509.18237-1-peter.ujfalusi@linux.intel.com> <20261007132509.18237-2-peter.ujfalusi@linux.intel.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-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_LOW(-1.00)[suse.de:dkim]; 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)[-0.998]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_TLS_ALL(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[intel.com:email,suse.de:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Action: no action X-Spam-Score: -4.51 X-Spam-Level: X-Rspamd-Queue-Id: D0DE61F443 On Wed, 07 Oct 2026 15:25:06 +0200, Peter Ujfalusi wrote: > > snd_compr_allocate_buffer() unconditionally overwrites > stream->runtime->buffer with a freshly kmalloc'd buffer whenever the > driver has no ops->copy and no preallocated dma_buffer_p. SET_PARAMS > is permitted repeatedly while the stream is in the OPEN state, so a > local process can loop SNDRV_COMPRESS_SET_PARAMS and leak the > previous buffer on every call, exhausting kernel memory. > > Free any framework-owned buffer before replacing it, mirroring the > ownership check already used in snd_compr_free(). > > Fixes: b21c60a4edd2 ("ALSA: core: add support for compress_offload") > Cc: stable@vger.kernel.org > Signed-off-by: Peter Ujfalusi > --- > sound/core/compress_offload.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > index 7c397b1c9231..c0ed76e1c844 100644 > --- a/sound/core/compress_offload.c > +++ b/sound/core/compress_offload.c > @@ -613,6 +613,10 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, > return -ENOMEM; > } > > + /* a prior SET_PARAMS may have left a framework-owned buffer behind */ > + if (!stream->runtime->dma_buffer_p) > + kfree(stream->runtime->buffer); > + I'd rather put to the else block above (or even better, if (stream->runtime->dma_buffer_p) block above that point). The code is specific to that condition, after all. thanks, Takashi