From nobody Wed Feb 11 16:22:22 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D1E7C77B7F for ; Fri, 5 May 2023 20:59:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231688AbjEEU7O (ORCPT ); Fri, 5 May 2023 16:59:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233185AbjEEU7L (ORCPT ); Fri, 5 May 2023 16:59:11 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B1EF44EE1; Fri, 5 May 2023 13:59:04 -0700 (PDT) Received: from W11-BEAU-MD.localdomain (unknown [76.135.27.212]) by linux.microsoft.com (Postfix) with ESMTPSA id 00CEF20EA205; Fri, 5 May 2023 13:59:03 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 00CEF20EA205 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1683320344; bh=Sy+d1mqucnUH/6CC12rPWwsujA9U/FCYF4OoGbHtNc0=; h=From:To:Cc:Subject:Date:From; b=kqbbjL167LT11+ZWPWWZ8LrgjqgxyKUm0TBDZBDHDeDEg+ZFonBELkxv3OKKaHCUV vxiICGhP8bjW7aY2DU0lTw3gu3CMBvw7mHKpXhQ1MAjMLERihdMf9hWPlonFm1i5I2 SKTcxR8gGr/4WR6SR2oRkNrZ9XmcN2PyppJ/wWVY= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, dan.carpenter@linaro.org Subject: [PATCH] tracing/user_events: Use long vs int for atomic bit ops Date: Fri, 5 May 2023 13:58:55 -0700 Message-Id: <20230505205855.6407-1-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Each event stores a int to track which bit to set/clear when enablement changes. On big endian 64-bit configurations, it's possible this could cause memory corruption when it's used for atomic bit operations. Use unsigned long for enablement values to ensure any possible corruption cannot occur. Downcast to int after mask for the bit target. Link: https://lore.kernel.org/all/6f758683-4e5e-41c3-9b05-9efc703e827c@kili= .mountain/ Fixes: dcb8177c1395 ("tracing/user_events: Add ioctl for disabling addresse= s") Reported-by: Dan Carpenter Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_u= ser.c index b1ecd7677642..e37c7f168c44 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -101,7 +101,7 @@ struct user_event_enabler { unsigned long addr; =20 /* Track enable bit, flags, etc. Aligned for bitops. */ - unsigned int values; + unsigned long values; }; =20 /* Bits 0-5 are for the bit to update upon enable/disable (0-63 allowed) */ @@ -116,7 +116,9 @@ struct user_event_enabler { /* Only duplicate the bit value */ #define ENABLE_VAL_DUP_MASK ENABLE_VAL_BIT_MASK =20 -#define ENABLE_BITOPS(e) ((unsigned long *)&(e)->values) +#define ENABLE_BITOPS(e) (&(e)->values) + +#define ENABLE_BIT(e) ((int)((e)->values & ENABLE_VAL_BIT_MASK)) =20 /* Used for asynchronous faulting in of pages */ struct user_event_enabler_fault { @@ -423,9 +425,9 @@ static int user_event_enabler_write(struct user_event_m= m *mm, =20 /* Update bit atomically, user tracers must be atomic as well */ if (enabler->event && enabler->event->status) - set_bit(enabler->values & ENABLE_VAL_BIT_MASK, ptr); + set_bit(ENABLE_BIT(enabler), ptr); else - clear_bit(enabler->values & ENABLE_VAL_BIT_MASK, ptr); + clear_bit(ENABLE_BIT(enabler), ptr); =20 kunmap_local(kaddr); unpin_user_pages_dirty_lock(&page, 1, true); @@ -440,8 +442,7 @@ static bool user_event_enabler_exists(struct user_event= _mm *mm, struct user_event_enabler *next; =20 list_for_each_entry_safe(enabler, next, &mm->enablers, link) { - if (enabler->addr =3D=3D uaddr && - (enabler->values & ENABLE_VAL_BIT_MASK) =3D=3D bit) + if (enabler->addr =3D=3D uaddr && ENABLE_BIT(enabler) =3D=3D bit) return true; } =20 @@ -2272,7 +2273,7 @@ static long user_events_ioctl_unreg(unsigned long uar= g) =20 list_for_each_entry_safe(enabler, next, &mm->enablers, link) if (enabler->addr =3D=3D reg.disable_addr && - (enabler->values & ENABLE_VAL_BIT_MASK) =3D=3D reg.disable_bit) { + ENABLE_BIT(enabler) =3D=3D reg.disable_bit) { set_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler)); =20 if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler))) base-commit: 3862f86c1529fa0016de6344eb974877b4cd3838 --=20 2.25.1