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b=I2PXYwUfHKVhRd04ZpplziNuij+mxN7EwKy1IMNwb5e+9HDQViAc4JYy+wdvPFEQtW86nA E/V4y5vudMbReaDg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 689DD13A23; Mon, 3 Mar 2025 15:56:40 +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 nrbhFzjRxWccGAAAD6G6ig (envelope-from ); Mon, 03 Mar 2025 15:56:40 +0000 Date: Mon, 03 Mar 2025 16:56:39 +0100 Message-ID: <87y0xmcdl4.wl-tiwai@suse.de> From: Takashi Iwai To: Luiz Augusto von Dentz Cc: Takashi Iwai , Luiz Augusto von Dentz , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Is commit 4d94f0555827 safe? In-Reply-To: References: <87a5a3ah2y.wl-tiwai@suse.de> <877c56dub7.wl-tiwai@suse.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-bluetooth@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=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: ACDA41F444 X-Spam-Level: X-Spamd-Result: default: False [-1.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; SUBJECT_ENDS_QUESTION(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)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FREEMAIL_TO(0.00)[gmail.com]; ARC_NA(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_TWO(0.00)[2]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim,suse.de:mid,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,syzkaller.appspot.com:url] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -1.01 X-Spam-Flag: NO On Mon, 03 Mar 2025 16:50:37 +0100, Luiz Augusto von Dentz wrote: > > Hi Takashi, > > On Mon, Mar 3, 2025 at 10:10 AM Takashi Iwai wrote: > > > > On Mon, 03 Mar 2025 15:57:16 +0100, > > Luiz Augusto von Dentz wrote: > > > > > > Hi Takashi, > > > > > > Well the assumption was that because we are doing a copy of the struct > > > being unregistered/freed would never cause any errors, so to trigger > > > something like UAF like the comment was suggesting the function > > > callback would need to be unmapped so even if the likes of iso_exit is > > > called it function (e.g. iso_connect_cfm) remains in memory. > > > > But it doesn't guarantee that the callback function would really > > work. e.g. if the callback accesses some memory that was immediately > > freed after the unregister call, it will lead to a UAF, even though > > the function itself is still present on the memory. > > > > That said, the current situation makes hard to judge the object life > > time. > > > > > You can find the previous version here: > > > > > > https://syzkaller.appspot.com/text?tag=Patch&x=100c0de8580000 > > > > > > Problem with it was that it is invalid to unlock and relock like that. > > > > Thanks for the pointer! > > > > > > BTW, I saw another patch posted to replace the mutex with spinlock > > (and you replied later on that it's been already fixed). > > Is it an acceptable approach at all? > > I don't remember if I saw that, but yeah anything that makes the issue > go away, and doesn't create new problems, would probably be > acceptable. I saw this one: https://lore.kernel.org/all/20230907122234.146449-1-william.xuanziyang@huawei.com/ Takashi