* [PATCH] usb: gadget: function: Fix returning incorrect PNP string @ 2022-01-05 4:04 Wei Ming Chen 2022-01-06 14:35 ` Greg KH 0 siblings, 1 reply; 4+ messages in thread From: Wei Ming Chen @ 2022-01-05 4:04 UTC (permalink / raw) To: linux-kernel; +Cc: linux-usb, gregkh, balbi, maze, Wei Ming Chen There will be 2 leading bytes indicating the total length of the PNP string, so I think we should add value by 2, otherwise the PNP string copied to user will not contain the last 2 bytes Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com> --- drivers/usb/gadget/function/f_printer.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c index abec5c58f525..3fb00fd0b5ee 100644 --- a/drivers/usb/gadget/function/f_printer.c +++ b/drivers/usb/gadget/function/f_printer.c @@ -1005,9 +1005,11 @@ static int printer_func_setup(struct usb_function *f, break; } value = strlen(dev->pnp_string); + memcpy(buf + 2, dev->pnp_string, value); + + value += 2; buf[0] = (value >> 8) & 0xFF; buf[1] = value & 0xFF; - memcpy(buf + 2, dev->pnp_string, value); DBG(dev, "1284 PNP String: %x %s\n", value, dev->pnp_string); break; -- 2.25.1 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] usb: gadget: function: Fix returning incorrect PNP string 2022-01-05 4:04 [PATCH] usb: gadget: function: Fix returning incorrect PNP string Wei Ming Chen @ 2022-01-06 14:35 ` Greg KH 2022-01-07 2:37 ` 陳偉銘 0 siblings, 1 reply; 4+ messages in thread From: Greg KH @ 2022-01-06 14:35 UTC (permalink / raw) To: Wei Ming Chen; +Cc: linux-kernel, linux-usb, balbi, maze On Wed, Jan 05, 2022 at 12:04:39PM +0800, Wei Ming Chen wrote: > There will be 2 leading bytes indicating the total length of > the PNP string, so I think we should add value by 2, otherwise > the PNP string copied to user will not contain the last 2 bytes > > Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com> > --- > drivers/usb/gadget/function/f_printer.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c > index abec5c58f525..3fb00fd0b5ee 100644 > --- a/drivers/usb/gadget/function/f_printer.c > +++ b/drivers/usb/gadget/function/f_printer.c > @@ -1005,9 +1005,11 @@ static int printer_func_setup(struct usb_function *f, > break; > } > value = strlen(dev->pnp_string); > + memcpy(buf + 2, dev->pnp_string, value); > + > + value += 2; > buf[0] = (value >> 8) & 0xFF; > buf[1] = value & 0xFF; > - memcpy(buf + 2, dev->pnp_string, value); > DBG(dev, "1284 PNP String: %x %s\n", value, > dev->pnp_string); > break; > -- > 2.25.1 > Are you sure this is correct? How is this related to this recent thread: https://lore.kernel.org/all/CAKjGFBUdjXcZoVV4jdrgTz4rKThTfZAK4CqreKmBZ4KHE+K1GA@mail.gmail.com/#t your change is different from what is proposed there, why? thanks, greg k-h ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] usb: gadget: function: Fix returning incorrect PNP string 2022-01-06 14:35 ` Greg KH @ 2022-01-07 2:37 ` 陳偉銘 2022-01-26 12:21 ` Greg KH 0 siblings, 1 reply; 4+ messages in thread From: 陳偉銘 @ 2022-01-07 2:37 UTC (permalink / raw) To: Greg KH; +Cc: linux-kernel, linux-usb, balbi, Maciej Żenczykowski Greg KH <gregkh@linuxfoundation.org> 於 2022年1月6日 週四 下午10:35寫道： > > On Wed, Jan 05, 2022 at 12:04:39PM +0800, Wei Ming Chen wrote: > > There will be 2 leading bytes indicating the total length of > > the PNP string, so I think we should add value by 2, otherwise > > the PNP string copied to user will not contain the last 2 bytes > > > > Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com> > > --- > > drivers/usb/gadget/function/f_printer.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c > > index abec5c58f525..3fb00fd0b5ee 100644 > > --- a/drivers/usb/gadget/function/f_printer.c > > +++ b/drivers/usb/gadget/function/f_printer.c > > @@ -1005,9 +1005,11 @@ static int printer_func_setup(struct usb_function *f, > > break; > > } > > value = strlen(dev->pnp_string); > > + memcpy(buf + 2, dev->pnp_string, value); > > + > > + value += 2; > > buf[0] = (value >> 8) & 0xFF; > > buf[1] = value & 0xFF; > > - memcpy(buf + 2, dev->pnp_string, value); > > DBG(dev, "1284 PNP String: %x %s\n", value, > > dev->pnp_string); > > break; > > -- > > 2.25.1 > > > > Are you sure this is correct? > > How is this related to this recent thread: > https://lore.kernel.org/all/CAKjGFBUdjXcZoVV4jdrgTz4rKThTfZAK4CqreKmBZ4KHE+K1GA@mail.gmail.com/#t > > your change is different from what is proposed there, why? I didn’t notice this thread before I send this patch, I think the concept of my change is similar to Volodymyr Lisivka’s change, he/she introduced a separate variable for the PNP string length, I think it may be clearer and more readable than just “value += 2” Another thing that I am not too sure whether I am correct is this line of code DBG(dev, "1284 PNP String: %x %s\n", value, dev->pnp_string); What Volodymyr Lisivka changed is like this DBG(dev, "1284 PNP String: %x %s\n", pnp_length, dev->pnp_string); In my change, “value” equals to “pnp_length + 2” in Volodymyr Lisivka’s change, and I think we should print “the PNP string length + 2” instead of “the PNP string length”? > > thanks, > > greg k-h thanks, Wei Ming Chen ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] usb: gadget: function: Fix returning incorrect PNP string 2022-01-07 2:37 ` 陳偉銘 @ 2022-01-26 12:21 ` Greg KH 0 siblings, 0 replies; 4+ messages in thread From: Greg KH @ 2022-01-26 12:21 UTC (permalink / raw) To: 陳偉銘 Cc: linux-kernel, linux-usb, balbi, Maciej Żenczykowski On Fri, Jan 07, 2022 at 10:37:19AM +0800, 陳偉銘 wrote: > Greg KH <gregkh@linuxfoundation.org> 於 2022年1月6日 週四 下午10:35寫道： > > > > On Wed, Jan 05, 2022 at 12:04:39PM +0800, Wei Ming Chen wrote: > > > There will be 2 leading bytes indicating the total length of > > > the PNP string, so I think we should add value by 2, otherwise > > > the PNP string copied to user will not contain the last 2 bytes > > > > > > Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com> > > > --- > > > drivers/usb/gadget/function/f_printer.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c > > > index abec5c58f525..3fb00fd0b5ee 100644 > > > --- a/drivers/usb/gadget/function/f_printer.c > > > +++ b/drivers/usb/gadget/function/f_printer.c > > > @@ -1005,9 +1005,11 @@ static int printer_func_setup(struct usb_function *f, > > > break; > > > } > > > value = strlen(dev->pnp_string); > > > + memcpy(buf + 2, dev->pnp_string, value); > > > + > > > + value += 2; > > > buf[0] = (value >> 8) & 0xFF; > > > buf[1] = value & 0xFF; > > > - memcpy(buf + 2, dev->pnp_string, value); > > > DBG(dev, "1284 PNP String: %x %s\n", value, > > > dev->pnp_string); > > > break; > > > -- > > > 2.25.1 > > > > > > > Are you sure this is correct? > > > > How is this related to this recent thread: > > https://lore.kernel.org/all/CAKjGFBUdjXcZoVV4jdrgTz4rKThTfZAK4CqreKmBZ4KHE+K1GA@mail.gmail.com/#t > > > > your change is different from what is proposed there, why? > > I didn’t notice this thread before I send this patch, I think the > concept of my change is similar to Volodymyr Lisivka’s change, he/she > introduced a separate variable for the PNP string length, I think it > may be clearer and more readable than just “value += 2” > > > Another thing that I am not too sure whether I am correct is this line of code > > DBG(dev, "1284 PNP String: %x %s\n", value, > dev->pnp_string); > > What Volodymyr Lisivka changed is like this > > DBG(dev, "1284 PNP String: %x %s\n", pnp_length, > dev->pnp_string); > > In my change, “value” equals to “pnp_length + 2” in Volodymyr > Lisivka’s change, and I think we should print “the PNP string length + > 2” instead of “the PNP string length”? > I do not know, I suggest you two work together to get the correct fix submitted. thanks, greg k-h ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-01-26 12:21 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-01-05 4:04 [PATCH] usb: gadget: function: Fix returning incorrect PNP string Wei Ming Chen 2022-01-06 14:35 ` Greg KH 2022-01-07 2:37 ` 陳偉銘 2022-01-26 12:21 ` Greg KH
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