From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EBF802EB87E for ; Wed, 8 Oct 2025 06:56:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759906581; cv=none; b=jYG+CtbudSKkg7IXTdz2k9t5i5DJo+jx8Wj8EgqEoFiHHtDWXVPndBAZtJkgNiWfe8iFhPzHzng8b1aDVaE90FwqjO5GZ1oLspsqS3jw76fEJMo5TIVNGLTI83x77R1+rw0IZ1901jVjtBrOnuZdkyARR1kLXIB+eNy8/WeivWQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759906581; c=relaxed/simple; bh=sYmJtnPIK7dPcICS0RFXNpoom+Swr58wH6UXsXIXIV8=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=mFVOYrqBwmEiICKmkPQcdpqsbgoERRRwAZBast1czW0Bn3GyT6tfQyemOsb57fXbwGibs4IdhQ9nQ3d5EvCG1cqTcn6iXVv3ebMoVrLOYBrTkmmWUIWMbEfV7tuHbY4ZwnqxXv51FEwNN7eoty+xyb0B8eGwI+CWNfeUUgyaHG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UcKv5YBe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UcKv5YBe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9720CC19421 for ; Wed, 8 Oct 2025 06:56:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759906580; bh=sYmJtnPIK7dPcICS0RFXNpoom+Swr58wH6UXsXIXIV8=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=UcKv5YBeoFquORtVxTbExHBg04mlDxbkyFgTu0Kkyk+UIXUK5pdynkdr7bu1/N3tg 9FJfbfPGddeLp/70ObY/f4vp1XqyzdOwynz5GFzSekp9UgfBsQ6vLZ5jAavtZpW7qW 5VoG5z1tjGF8RUCbESzj1aMaW7zV1LOoiwTU3uHevVtN+D0OtWCPDyN+5eE65h++6m 1fKcsTqtmj7y0IRwgIp6nefif3ai+/kad9+gu9CaQLVsJLHw96whgb0YsqpanUZCFp BxvIN0fsAVrGVrE62EodTErjU+EXTG77j+zi5lIkvO4nF4lNBg1PXkkQN4U9j1kBEs y8dFN6JkEL8Fg== Received: by mail-ed1-f46.google.com with SMTP id 4fb4d7f45d1cf-6398ff5fbd3so6475948a12.2 for ; Tue, 07 Oct 2025 23:56:20 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCVKkWmhnCrC4tOGGNz6ImDpKOGXwtSvwpZW6On+RbBaP5JNweWiXEVa6F0/jUhVgz836WLgtY6zj13XrtyL@vger.kernel.org X-Gm-Message-State: AOJu0YzV9bmBrv4pTyWu001VgUwotKF5sOdkQW5cTf5dG69QsuFU6WIv 3jPaXguRV4hAK5zh5rbKoUqtQY/B/ExY+7SV0AtSNy0lv7ahGbAoNczXc86RAZl2whDzyWMzXiX CeeCK6HaZfWUzmolZBuBl31Jf/XNph+o= X-Google-Smtp-Source: AGHT+IFss3JE8O+RIRAqixQEEDjegTvXXRCXuS71Xh1IU/NNvYrzdMjNqKL6UI8w0f4U4/7eQlaw3rawLE3rTOZMF0I= X-Received: by 2002:a17:906:c105:b0:b3e:907c:9e26 with SMTP id a640c23a62f3a-b50ac5cfaf7mr239322766b.59.1759906579179; Tue, 07 Oct 2025 23:56:19 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20251006114507.371788-1-aha310510@gmail.com> In-Reply-To: <20251006114507.371788-1-aha310510@gmail.com> From: Namjae Jeon Date: Wed, 8 Oct 2025 15:56:06 +0900 X-Gmail-Original-Message-ID: X-Gm-Features: AS18NWBt4-ax8frC1iEO2ZNytLZMzrWDiVOFF6Qdq15mYbUfbImMgl-fSvih7Ro Message-ID: Subject: Re: [PATCH] exfat: fix out-of-bounds in exfat_nls_to_ucs2() To: Jeongjun Park Cc: sj1557.seo@samsung.com, yuezhang.mo@sony.com, viro@zeniv.linux.org.uk, pali@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+98cc76a76de46b3714d4@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Oct 6, 2025 at 8:45=E2=80=AFPM Jeongjun Park = wrote: > Hi Jeongjun, > After the loop that converts characters to ucs2 ends, the variable i > may be greater than or equal to len. However, when checking whether the > last byte of p_cstring is NULL, the variable i is used as is, resulting > in an out-of-bounds read if i >=3D len. > > Therefore, to prevent this, we need to modify the function to check > whether i is less than len, and if i is greater than or equal to len, > to check p_cstring[len - 1] byte. I think we need to pass FSLABEL_MAX - 1 to exfat_nls_to_utf16, not FSLABEL_= MAX. Can you check it and update the patch? Thanks. > > Cc: > Reported-by: syzbot+98cc76a76de46b3714d4@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3D98cc76a76de46b3714d4 > Fixes: 370e812b3ec1 ("exfat: add nls operations") > Signed-off-by: Jeongjun Park > --- > fs/exfat/nls.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c > index 8243d94ceaf4..a52f3494eb20 100644 > --- a/fs/exfat/nls.c > +++ b/fs/exfat/nls.c > @@ -616,7 +616,7 @@ static int exfat_nls_to_ucs2(struct super_block *sb, > unilen++; > } > > - if (p_cstring[i] !=3D '\0') > + if (p_cstring[min(i, len - 1)] !=3D '\0') > lossy |=3D NLS_NAME_OVERLEN; > > *uniname =3D '\0'; > --