Messages in this thread Patch in this message | | | Date | Mon, 2 Nov 2020 13:11:50 +0100 | From | "" <> | Subject | Re: [PATCH 1/2] misc: c2port: core: Make copying name from userspace more secure |
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On Mon, Nov 02, 2020 at 11:49:03AM +0000, Lee Jones wrote: > On Mon, 02 Nov 2020, David Laight wrote: > > > From: Lee Jones > > > Sent: 02 November 2020 11:12 > > > > > > strncpy() may not provide a NUL terminator, which means that a 1-byte > > > leak would be possible *if* this was ever copied to userspace. Ensure > > > the buffer will always be NUL terminated by using the kernel's > > > strscpy() which a) uses the destination (instead of the source) size > > > as the bytes to copy and b) is *always* NUL terminated. > > > > > > Cc: Rodolfo Giometti <giometti@enneenne.com> > > > Cc: "Eurotech S.p.A" <info@eurotech.it> > > > Reported-by: Geert Uytterhoeven <geert+renesas@glider.be> > > > Acked-by: Arnd Bergmann <arnd@arndb.de> > > > Signed-off-by: Lee Jones <lee.jones@linaro.org> > > > --- > > > drivers/misc/c2port/core.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/misc/c2port/core.c b/drivers/misc/c2port/core.c > > > index 80d87e8a0bea9..b96444ec94c7e 100644 > > > --- a/drivers/misc/c2port/core.c > > > +++ b/drivers/misc/c2port/core.c > > > @@ -923,7 +923,7 @@ struct c2port_device *c2port_device_register(char *name, > > > } > > > dev_set_drvdata(c2dev->dev, c2dev); > > > > > > - strncpy(c2dev->name, name, C2PORT_NAME_LEN - 1); > > > + strscpy(c2dev->name, name, sizeof(c2dev->name)); > > > > strscpy() doesn't zero fill so if the memory isn't zeroed > > and a 'blind' copy to user of the structure is done > > then more data is leaked. > > > > strscpy() may be better, but rational isn't right. > > The original patch zeroed the data too, but I was asked to remove that > part [0]. In your opinion, should it be reinstated? > > [0] https://lore.kernel.org/patchwork/patch/1272290/
Just keep the kzalloc() part of the patch, this portion makes no sense to me. But if you REALLY want to get it correct, call dev_set_name() instead please, as that is what it is there for.
thanks,
greg k-h
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