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Wed, 4 Jun 2025 10:47:18 +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 OfIzDTYkQGgyLQAAD6G6ig (envelope-from ); Wed, 04 Jun 2025 10:47:18 +0000 From: Nikolay Borisov To: x86@kernel.org Cc: pawan.kumar.gupta@linux.intel.com, peterz@infradead.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, Nikolay Borisov Subject: [PATCH] x86/its: Always return a writable page for dynamic thunks Date: Wed, 4 Jun 2025 13:47:15 +0300 Message-ID: <20250604104715.700149-1-nik.borisov@suse.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: AAB4333741 X-Rspamd-Action: no action X-Spam-Flag: NO X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; MIME_TRACE(0.00)[0:+]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.com:mid,suse.com:dkim,suse.com:email]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; DKIM_TRACE(0.00)[suse.com:+] X-Spam-Score: -3.01 X-Spam-Level: Content-Type: text/plain; charset="utf-8" its_alloc unconditionally allocates and return a ROX page, but setting it RW is predicated on its_mod being set. This can cause a #GP on the memset in its_allocate_thunk() if its_mod is not set. Since the function always returns a page, ensure it's always set writable so it can be initialized properly. Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches") Signed-off-by: Nikolay Borisov --- arch/x86/kernel/alternative.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index ecfe7b497cad..191e909636a5 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -199,6 +199,8 @@ static void *its_alloc(void) if (!page) return NULL; =20 + execmem_make_temp_rw(page, PAGE_SIZE); + #ifdef CONFIG_MODULES if (its_mod) { void *tmp =3D krealloc(its_mod->its_page_array, @@ -210,7 +212,6 @@ static void *its_alloc(void) its_mod->its_page_array =3D tmp; its_mod->its_page_array[its_mod->its_num_pages++] =3D page; =20 - execmem_make_temp_rw(page, PAGE_SIZE); } #endif /* CONFIG_MODULES */ =20 --=20 2.43.0