From: Petko Manolov <petkan@nucleusys.com> To: Anant Thazhemadam <anant.thazhemadam@gmail.com> Cc: linux-kernel-mentees@lists.linuxfoundation.org, syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com, "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees][PATCH] rtl8150: set memory to all 0xFFs on failed register reads Date: Wed, 16 Sep 2020 09:19:46 +0300 [thread overview] Message-ID: <20200916061946.GA38262@p310> (raw) In-Reply-To: <20200916050540.15290-1-anant.thazhemadam@gmail.com> On 20-09-16 10:35:40, Anant Thazhemadam wrote: > get_registers() copies whatever memory is written by the > usb_control_msg() call even if the underlying urb call ends up failing. Not true, memcpy() is only called if "ret" is positive. > If get_registers() fails, or ends up reading 0 bytes, meaningless and junk > register values would end up being copied over (and eventually read by the > driver), and since most of the callers of get_registers() don't check the > return values of get_registers() either, this would go unnoticed. usb_control_msg() returns negative on error (look up usb_internal_control_msg() to see for yourself) so it does not go unnoticed. If for some reason it return zero, nothing is copied. Also, if usb transfer fail no register values are being copied anywhere. Your patch also allows for memcpy() to be called with 'size' either zero or greater than the allocated buffer size. Please, look at the code carefully. > It might be a better idea to try and mirror the PCI master abort > termination and set memory to 0xFFs instead in such cases. I wasn't aware drivers are now responsible for filling up the memory with anything. Does not sound like a good idea to me. > Fixes: https://syzkaller.appspot.com/bug?extid=abbc768b560c84d92fd3 > Reported-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com > Tested-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com > Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com> Well, NACK from me. cheers, Petko > --- > drivers/net/usb/rtl8150.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c > index 733f120c852b..04fca7bfcbcb 100644 > --- a/drivers/net/usb/rtl8150.c > +++ b/drivers/net/usb/rtl8150.c > @@ -162,8 +162,13 @@ static int get_registers(rtl8150_t * dev, u16 indx, u16 size, void *data) > ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), > RTL8150_REQ_GET_REGS, RTL8150_REQT_READ, > indx, 0, buf, size, 500); > - if (ret > 0 && ret <= size) > + > + if (ret < 0) > + memset(data, 0xff, size); > + > + else > memcpy(data, buf, ret); > + > kfree(buf); > return ret; > } > @@ -276,7 +281,7 @@ static int write_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 reg) > > static inline void set_ethernet_addr(rtl8150_t * dev) > { > - u8 node_id[6]; > + u8 node_id[6] = {0}; > > get_registers(dev, IDR, sizeof(node_id), node_id); > memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id)); > -- > 2.25.1 > >
WARNING: multiple messages have this Message-ID (diff)
From: Petko Manolov <petkan@nucleusys.com> To: Anant Thazhemadam <anant.thazhemadam@gmail.com> Cc: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com, netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>, linux-kernel-mentees@lists.linuxfoundation.org, "David S. Miller" <davem@davemloft.net> Subject: Re: [Linux-kernel-mentees] [PATCH] rtl8150: set memory to all 0xFFs on failed register reads Date: Wed, 16 Sep 2020 09:19:46 +0300 [thread overview] Message-ID: <20200916061946.GA38262@p310> (raw) In-Reply-To: <20200916050540.15290-1-anant.thazhemadam@gmail.com> On 20-09-16 10:35:40, Anant Thazhemadam wrote: > get_registers() copies whatever memory is written by the > usb_control_msg() call even if the underlying urb call ends up failing. Not true, memcpy() is only called if "ret" is positive. > If get_registers() fails, or ends up reading 0 bytes, meaningless and junk > register values would end up being copied over (and eventually read by the > driver), and since most of the callers of get_registers() don't check the > return values of get_registers() either, this would go unnoticed. usb_control_msg() returns negative on error (look up usb_internal_control_msg() to see for yourself) so it does not go unnoticed. If for some reason it return zero, nothing is copied. Also, if usb transfer fail no register values are being copied anywhere. Your patch also allows for memcpy() to be called with 'size' either zero or greater than the allocated buffer size. Please, look at the code carefully. > It might be a better idea to try and mirror the PCI master abort > termination and set memory to 0xFFs instead in such cases. I wasn't aware drivers are now responsible for filling up the memory with anything. Does not sound like a good idea to me. > Fixes: https://syzkaller.appspot.com/bug?extid=abbc768b560c84d92fd3 > Reported-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com > Tested-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com > Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com> Well, NACK from me. cheers, Petko > --- > drivers/net/usb/rtl8150.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c > index 733f120c852b..04fca7bfcbcb 100644 > --- a/drivers/net/usb/rtl8150.c > +++ b/drivers/net/usb/rtl8150.c > @@ -162,8 +162,13 @@ static int get_registers(rtl8150_t * dev, u16 indx, u16 size, void *data) > ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), > RTL8150_REQ_GET_REGS, RTL8150_REQT_READ, > indx, 0, buf, size, 500); > - if (ret > 0 && ret <= size) > + > + if (ret < 0) > + memset(data, 0xff, size); > + > + else > memcpy(data, buf, ret); > + > kfree(buf); > return ret; > } > @@ -276,7 +281,7 @@ static int write_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 reg) > > static inline void set_ethernet_addr(rtl8150_t * dev) > { > - u8 node_id[6]; > + u8 node_id[6] = {0}; > > get_registers(dev, IDR, sizeof(node_id), node_id); > memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id)); > -- > 2.25.1 > > _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
next prev parent reply other threads:[~2020-09-16 7:02 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-16 5:05 [Linux-kernel-mentees][PATCH] rtl8150: set memory to all 0xFFs on failed register reads Anant Thazhemadam 2020-09-16 5:05 ` [Linux-kernel-mentees] [PATCH] " Anant Thazhemadam 2020-09-16 6:19 ` Petko Manolov [this message] 2020-09-16 6:19 ` Petko Manolov 2020-09-16 13:38 ` [Linux-kernel-mentees][PATCH] " Anant Thazhemadam 2020-09-16 13:38 ` [Linux-kernel-mentees] [PATCH] " Anant Thazhemadam 2020-09-16 6:22 ` [Linux-kernel-mentees][PATCH] " Greg KH 2020-09-16 6:22 ` [Linux-kernel-mentees] [PATCH] " Greg KH 2020-09-16 6:39 ` [Linux-kernel-mentees][PATCH] " Petko Manolov 2020-09-16 6:39 ` [Linux-kernel-mentees] [PATCH] " Petko Manolov 2020-09-16 13:40 ` [Linux-kernel-mentees][PATCH] " Anant Thazhemadam 2020-09-16 13:40 ` [Linux-kernel-mentees] [PATCH] " Anant Thazhemadam
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