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Sun, 16 Aug 2026 10:40:13 +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 FsYDHo2TgWrjaAAAD6G6ig (envelope-from ); Sun, 16 Aug 2026 10:40:13 +0000 Date: Sun, 16 Aug 2026 12:40:13 +0200 Message-ID: <87zeymcprm.wl-tiwai@suse.de> From: Takashi Iwai To: Ivy Lopez Cc: Greg Kroah-Hartman , Takashi Iwai , Kees Cook , Christophe JAILLET , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+2280f1cca5e6b0c353e4@syzkaller.appspotmail.com Subject: Re: [PATCH] usb: gadget: f_midi2: fix use-after-free in string attribute show path In-Reply-To: <20260816005434.34018-1-skunkolee@gmail.com> References: <20260816005434.34018-1-skunkolee@gmail.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@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: C92D53DFB X-Spamd-Result: default: False [-2.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; 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)[]; URIBL_BLOCKED(0.00)[suse.de:mid,suse.de:email,suse.de:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,syzkaller.appspot.com:url,appspotmail.com:email]; TO_MATCH_ENVRCPT_ALL(0.00)[]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_TRACE(0.00)[0:+]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; FREEMAIL_TO(0.00)[gmail.com]; FREEMAIL_ENVRCPT(0.00)[gmail.com,wanadoo.fr]; FREEMAIL_CC(0.00)[linuxfoundation.org,suse.de,kernel.org,wanadoo.fr,vger.kernel.org,syzkaller.appspotmail.com]; RCVD_COUNT_TWO(0.00)[2]; RCPT_COUNT_SEVEN(0.00)[8]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[2280f1cca5e6b0c353e4]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,appspotmail.com:email,suse.de:mid,suse.de:email,suse.de:dkim,syzkaller.appspot.com:url] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO On Sun, 16 Aug 2026 02:54:33 +0200, Ivy Lopez wrote: > > f_midi2_opts_str_show() takes the string lock internally, but its > callers dereference the opts->info. pointer before calling it, > outside the lock. This races with f_midi2_opts_str_store(), which > frees the old string under opts->lock when the attribute is written > concurrently, the show path can read a pointer that gets freed > before the lock inside str_show() is even taken. > > Change f_midi2_opts_str_show() to take a pointer to the string field, > matching the existing pattern in f_midi2_opts_str_store(), and > dereference it only after the lock is held. Update all three callers > (iface_name, block name, and the EP string option macro) accordingly. > > Reported-by: syzbot+2280f1cca5e6b0c353e4@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=2280f1cca5e6b0c353e4 > Signed-off-by: Ivy Lopez Reviewed-by: Takashi Iwai thanks, Takashi