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Tue, 8 Sep 2026 14:24:44 +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 j+2qLawaoGq3BwAAD6G6ig (envelope-from ); Tue, 08 Sep 2026 14:24:44 +0000 Date: Tue, 08 Sep 2026 16:24:29 +0200 Message-ID: <87ik4fq0rm.wl-tiwai@suse.de> From: Takashi Iwai To: Kazuki Hanai Cc: Jaroslav Kysela , Takashi Iwai , linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] ALSA: us122l: Prevent write upgrades for read mappings In-Reply-To: <20260908110053.2950767-1-hnkz.64@gmail.com> References: <20260908110053.2950767-1-hnkz.64@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-Rspamd-Queue-Id: EA7D521ADF X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Level: X-Rspamd-Action: no action X-Spamd-Result: default: False [-2.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; 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)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; ARC_NA(0.00)[]; FREEMAIL_TO(0.00)[gmail.com]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(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,suse.de:dkim,suse.de:mid] X-Spam-Flag: NO On Tue, 08 Sep 2026 13:00:53 +0200, Kazuki Hanai wrote: > > The hwdep mmap callback rejects read-buffer mappings that are initially > writable, but leaves VM_MAYWRITE set on mappings created with PROT_READ. > A process that can open the hwdep node O_RDWR can later use mprotect() to > make the mapping writable. > > The read allocation begins with struct usb_stream. Its read_size member is > used by the fault handler to decide which pages belong to the read buffer. > The read VMA intentionally remains expandable because pcm_usb_stream uses > mremap() after reading that size. Changing read_size first can therefore > map and access pages beyond the allocation. The same member is also > consumed by usb_stream_free(), where changing it can make > free_pages_exact() release pages outside the allocation. > > Clear VM_MAYWRITE for read-buffer mappings after rejecting an initially > writable VMA. This keeps the separate output-buffer mapping writable while > preventing later permission upgrades. > > Fixes: 030a07e44129 ("ALSA: Add USB US122L driver") > Cc: stable@vger.kernel.org > Signed-off-by: Kazuki Hanai Applied now. Thanks. Takashi