From nobody Sat Feb 7 11:55:55 2026 Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E4F4C314D34 for ; Tue, 27 Jan 2026 04:02:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.70 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769486541; cv=none; b=fUAK/T2f4PCpR/j/O1/0bcFHEQIu1qNXNdLsPsMAxREByexpmJXM6UYZ2GmaX5cc2Aw9yzdUAY5N1Ka/aFSG3pvCVgz5sEpclp9cfmRlfE+XCkjH3iHW6YQRSL+XdeWx2XsWg0B+mEs4BlT75eZho40Lo3iNferKnhztUfVNgOk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769486541; c=relaxed/simple; bh=ivff23mYnJjSQ3hkWxehzBzSnR2j1Rhi0iFy31jzlhk=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=guETK55xKcoYRO8ya36W0iQf6zCQ6kyl34N74jowKBJK00jNSxgll4WskgMGkpFFxzTrxC4oDn9j4trH+mkcGc0j1EhP/whJ/c4HHzNKU8h0kWu++wqV2SRXKRJkgsm5ZOoqM3PnaJyyYSsmY9GELmnu8U8mjOsRfePPX8wxwMY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f70.google.com with SMTP id 006d021491bc7-662c6ddd80dso10361664eaf.2 for ; Mon, 26 Jan 2026 20:02:19 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769486539; x=1770091339; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=JutyKOD25WCpc/S+UlIx8d9zdaPoRnvPwn26QF969nc=; b=cDI1aiT+POWlOS7GpxrI2dz605novSXjdeTQwgG1nam6xjd4ZaBzaeVcZJZyIMXOsR Gb9DMEXYNtT2IILcc97y811jRGj1BVy00S2LEW441cYcs8JXpjRX2cyxacnsbreliQNS Pwz5MrkSO9VaBSDC3i3yDuNAI47PEDSd/QjT5tIPeKofY+bwPhL6khH/gts+aiWB0lRL I7I0IYU40maqMQ33ryVXq4ZuImUS1O7x0hhtubAFE/hmy+7Ixw5qIkUrgx0es//d5NYE 7W62ViYzUjSwaKbm239CEaLvAe+/cPDNUyJpOTWrvp1MexzS/bWPLKWSZWwS0rQd8+gg xviA== X-Gm-Message-State: AOJu0YysiYAWDcbSCBrD15hvjlQsqOrF7w7SFr5xo/F1/LiWjB+AkiW3 E4bQI0hKHgoIRpRGbVqtNb9IjVfGBRn7j6+iOGtw1tWGa+857OPXo03fhbDaQ48AZ6cDTbEnvj/ ZGtQfFQel0vu+JfbmrKOMcaD/BLlBw5T3vmgVZEW5oCO5oRxVAHHEZy4eQBE= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:2007:b0:662:8b01:c7cb with SMTP id 006d021491bc7-662f2177ecamr245370eaf.84.1769486538768; Mon, 26 Jan 2026 20:02:18 -0800 (PST) Date: Mon, 26 Jan 2026 20:02:18 -0800 In-Reply-To: <69780fd2.050a0220.c9109.000a.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <697838ca.050a0220.c9109.0010.GAE@google.com> Subject: Forwarded: [PATCH] mm: Fix KASAN-induced recursive page faults in ptlock_ptr From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH] mm: Fix KASAN-induced recursive page faults in ptlock_ptr Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git= master When pte_offset_map_rw_nolock() is called during signal frame setup in the ret_from_fork path, KASAN instrumentation of ptlock_ptr() can trigger recursive page faults. The KASAN shadow memory access itself may cause a page fault while already handling a page fault. In RT priority contexts (SCHED_FIFO), this recursive faulting prevents the task from yielding, causing RCU stalls as the grace period kthread cannot get CPU time. Disable KASAN instrumentation for both variants of ptlock_ptr() to prevent this recursion. Reported-by: syzbot+42836f91edd58eb82c6a@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=3D42836f91edd58eb82c6a Signed-off-by: Deepanshu Kartikey --- include/linux/mm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f0d5be9dc736..093ea042f973 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3235,7 +3235,7 @@ void __init ptlock_cache_init(void); bool ptlock_alloc(struct ptdesc *ptdesc); void ptlock_free(struct ptdesc *ptdesc); =20 -static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) +__no_sanitize_address static inline spinlock_t *ptlock_ptr(struct ptdesc *= ptdesc) { return ptdesc->ptl; } @@ -3253,7 +3253,7 @@ static inline void ptlock_free(struct ptdesc *ptdesc) { } =20 -static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) +__no_sanitize_address static inline spinlock_t *ptlock_ptr(struct ptdesc *= ptdesc) { return &ptdesc->ptl; } --=20 2.43.0