On Wed, Dec 13, 2023 at 03:15:15PM +0000, Hardevsinh Palaniya wrote: > Hello [1]@Bjorn Andersson, Please use appropriate mail list etiquette, and avoid HTML and top-posting in your responses. > > "strscpy_pad" itself takes care of null-terminated strings. So, there > will be no leak. Your strscpy_pad() will NUL-terminate and zero-pad up to 32 bytes. Following this the next line will write strlen(name) + sizeof(hdr) bytes to the FIFO. So if strlen(name) >= 32 you will read beyond the end of the zero-padded string. Regards, Bjorn > __________________________________________________________________ > > From: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx> > Sent: Tuesday, December 12, 2023 12:10 AM > To: Hardevsinh Palaniya <hardevsinh.palaniya@xxxxxxxxxxxxxxxxx> > Cc: agross@xxxxxxxxxx <agross@xxxxxxxxxx>; andersson@xxxxxxxxxx > <andersson@xxxxxxxxxx>; Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>; > Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>; > linux-arm-msm@xxxxxxxxxxxxxxx <linux-arm-msm@xxxxxxxxxxxxxxx>; > linux-remoteproc@xxxxxxxxxxxxxxx <linux-remoteproc@xxxxxxxxxxxxxxx>; > linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH] rpmsg: glink: Fix buffer overflow > > On Mon, Dec 11, 2023 at 09:32:20PM +0530, Hardevsinh Palaniya wrote: > > In qcom_glink_send_open_req() remove error: strcpy() 'channel->name' > > too large for 'req.name' (1010102 vs 32) > > > As far as I can tell, channel->name comes from the struct > rpmsg_channel_info->name, which is a 32-byte array, and all code paths > I > can find either uses strscpy() or explicitly NUL-terminates this > string. > I'm curious to know which path took us here. > > Signed-off-by: Hardevsinh Palaniya > <hardevsinh.palaniya@xxxxxxxxxxxxxxxxx> > > > > diff --git a/drivers/rpmsg/qcom_glink_native.c > b/drivers/rpmsg/qcom_glink_native.c > > index 82d460ff4777..2d6a592e1c72 100644 > > --- a/drivers/rpmsg/qcom_glink_native.c > > +++ b/drivers/rpmsg/qcom_glink_native.c > > @@ -479,7 +479,7 @@ static int qcom_glink_send_open_req(struct > qcom_glink *glink, > > req.msg.cmd = cpu_to_le16(GLINK_CMD_OPEN); > > req.msg.param1 = cpu_to_le16(channel->lcid); > > req.msg.param2 = cpu_to_le32(name_len); > > - strcpy(req.name, channel->name); > > + strscpy_pad(req.name, channel->name, sizeof(req.name)); > I think this patch is incomplete. While it makes sure we don't > overwrite > the stack. name_len is strlen(channel->name) + 1 and the amount of data > sent out is based on name_len. > As such, if you can get here with a @name of arbitrary length, then you > can control how much of the stack we're going to now leak to the > recipient. > Regards, > Bjorn > > > > ret = qcom_glink_tx(glink, &req, req_len, NULL, 0, true); > > if (ret) > > -- > > 2.25.1 > > > > > > References > > 1. mailto:quic_bjorande@xxxxxxxxxxx
