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Wed, 29 Jul 2026 06:33:25 +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 Q77LKLWeaWrGXQAAD6G6ig (envelope-from ); Wed, 29 Jul 2026 06:33:25 +0000 Date: Wed, 29 Jul 2026 08:33:25 +0200 Message-ID: <87mrva5mq2.wl-tiwai@suse.de> From: Takashi Iwai To: Deepanshu Kartikey Cc: perex@perex.cz, tiwai@suse.com, kees@kernel.org, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+b6cab840e6a85641c7ad@syzkaller.appspotmail.com Subject: Re: [PATCH] ALSA: ump: Fix double-free of ump->out_cvts on legacy rawmidi attach failure In-Reply-To: <20260729002333.11525-1-kartikey406@gmail.com> References: <20260729002333.11525-1-kartikey406@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-Score: -2.01 X-Spam-Level: X-Rspamd-Action: no action X-Rspamd-Queue-Id: E2E143E0F X-Spamd-Result: default: False [-2.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; SUSPICIOUS_RECIPS(1.50)[]; 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]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FREEMAIL_TO(0.00)[gmail.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]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_SEVEN(0.00)[7]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[b6cab840e6a85641c7ad]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,syzkaller.appspot.com:url,appspotmail.com:email] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO On Wed, 29 Jul 2026 02:23:33 +0200, Deepanshu Kartikey wrote: > > If snd_rawmidi_new() fails inside snd_ump_attach_legacy_rawmidi(), the > error path frees ump->out_cvts but leaves the pointer dangling. Since > ump->out_cvts is a field of the long-lived struct snd_ump_endpoint > (not the rawmidi device that failed to be created), it gets freed a > second time later during normal endpoint teardown, in > snd_ump_endpoint_free(), invoked via snd_rawmidi_free()'s > private_free callback when the sound card is released. This results > in a KASAN double-free/invalid-free. > > Clear ump->out_cvts to NULL after freeing it on the error path, so > the later unconditional kfree() in snd_ump_endpoint_free() becomes a > harmless no-op. > > Reported-by: syzbot+b6cab840e6a85641c7ad@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=b6cab840e6a85641c7ad > Signed-off-by: Deepanshu Kartikey The very same fix has been already merged in commit 70c977815af0d997feb2d0c5d284d55689bf7051 on sound git tree. thanks, Takashi