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[109.241.130.11]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2a1bbc6830sm39654466b.52.2026.09.18.03.03.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Sep 2026 03:03:38 -0700 (PDT) Sender: =?UTF-8?Q?Micha=C5=82_Nazarewicz?= From: =?utf-8?Q?Micha=C5=82?= Nazarewicz To: zjamg , Greg Kroah-Hartman Cc: Robert Baldyga , Felipe Balbi , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Yuchao Zhang , stable@vger.kernel.org Subject: Re: [RESEND PATCH 1/1] usb: gadget: f_fs: Fix NULL pointer dereference in FUNCTIONFS_ENDPOINT_DESC In-Reply-To: <20260918005438.81263-2-ndaugoing@gmail.com> References: <20260918005438.81263-1-ndaugoing@gmail.com> <20260918005438.81263-2-ndaugoing@gmail.com> Date: Fri, 18 Sep 2026 12:03:37 +0200 Message-ID: Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, Sep 18 2026, zjamg wrote: > From: Yuchao Zhang > > Fixes: c559a3534109 ("usb: gadget: f_fs: add ioctl returning ep descripto= r") > Cc: stable@vger.kernel.org > Signed-off-by: Yuchao Zhang Acked-by: Micha=C5=82 Nazarewicz > --- > drivers/usb/gadget/function/f_fs.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/func= tion/f_fs.c > index 43962e05eacf..c64a268e98a4 100644 > --- a/drivers/usb/gadget/function/f_fs.c > +++ b/drivers/usb/gadget/function/f_fs.c > @@ -1877,8 +1877,9 @@ static long ffs_epfile_ioctl(struct file *file, uns= igned code, > break; > case FUNCTIONFS_ENDPOINT_DESC: > { > + const struct usb_endpoint_descriptor *desc; > + struct usb_endpoint_descriptor desc1; > int desc_idx; > - struct usb_endpoint_descriptor desc1, *desc; >=20=20 > switch (epfile->ffs->gadget->speed) { > case USB_SPEED_SUPER: > @@ -1892,7 +1893,17 @@ static long ffs_epfile_ioctl(struct file *file, un= signed code, > desc_idx =3D 0; > } >=20=20 > - desc =3D epfile->ep->descs[desc_idx]; > + do { > + desc =3D epfile->ep->descs[desc_idx]; > + } while (!desc && --desc_idx >=3D 0); > + > + if (!desc) > + desc =3D epfile->ep->ep->desc; IIUC, this will never be non-NULL if all the descriptors are NULL. Then again, it probably won=E2=80=99t hurt, so dosen=E2=80=99t matter one way or= another. > + if (!desc) { > + ret =3D -EINVAL; > + break; > + } > + > memcpy(&desc1, desc, desc->bLength); >=20=20 > spin_unlock_irq(&epfile->ffs->eps_lock); --=20 Best regards =E3=83=9F=E3=83=8F=E3=82=A6 =E2=80=9C=F0=9D=93=B6=F0=9D=93=B2=F0=9D=93=B7= =F0=9D=93=AA86=E2=80=9D =E3=83=8A=E3=82=B6=E3=83=AC=E3=83=B4=E3=82=A3=E3=83= =84 =C2=ABIf at first you don=E2=80=99t succeed, give up skydiving=C2=BB