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Sun, 2 Mar 2025 09:59:34 +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 u7rnBwYsxGfeCgAAD6G6ig (envelope-from ); Sun, 02 Mar 2025 09:59:34 +0000 Date: Sun, 02 Mar 2025 10:59:33 +0100 Message-ID: <87a5a3ah2y.wl-tiwai@suse.de> From: Takashi Iwai To: Luiz Augusto von Dentz Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Is commit 4d94f0555827 safe? 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=US-ASCII X-Rspamd-Queue-Id: 51C4C1F770 X-Spam-Level: X-Spamd-Result: default: False [-2.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; SUBJECT_ENDS_QUESTION(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)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; FROM_EQ_ENVFROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid]; RCVD_COUNT_TWO(0.00)[2]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -2.51 X-Spam-Flag: NO [ I posted without the subject line mistakenly, so resent again; sorry if you have seen already read it ] Hi Luiz, due to the CVE assignment, I stumbled on the recent fix for BT hci_core, the commit 4d94f0555827 ("Bluetooth: hci_core: Fix sleeping function called from invalid context"), and wonder whether it's really safe. As already asked question at the patch review: https://patchwork.kernel.org/comment/26147087/ the code allows the callbacks to be called even after hci_unregister_cb() returns. Your assumption was that it's never called without the module removal, but isn't hci_unregister_cb() also called from iso_exit() which can be triggered via set_iso_socket_func() in mgmt.c? Also, any 3rd party module could call hci_unregister_cb() in a wild way, too -- even if the function still remains, it doesn't mean that you can call it safely if the caller already assumes it being unregistered. In addition to that, I feel what the patch does as a bit too heavy-lifting: it does kmalloc() and copy the whole hci_cb object, which isn't quite small for each. If the callback is still safe to call after RCU protection, you may just keep the hci_cb pointer instead of copying the whole content, too? I couldn't find v1 patch in the patchwork, so not sure whether this has been already discussed. If so, let me know. Thanks! Takashi