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Date: Wed, 12 Jan 2022 12:41:27 -0800 From: Kees Cook <keescook@...omium.org> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Arnd Bergmann <arnd@...db.de>, Jiri Prchal <jiri.prchal@...ignal.cz>, Ralph Siemsen <ralph.siemsen@...aro.org>, Mark Brown <broonie@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-hardening@...r.kernel.org Subject: Re: [PATCH] eeprom: at25: Restore missing allocation On Sat, Jan 08, 2022 at 01:36:12PM +0200, Andy Shevchenko wrote: > On Sat, Jan 8, 2022 at 1:01 PM Kees Cook <keescook@...omium.org> wrote: > > > > Building under CONFIG_FORTIFY_SOURCE=y and -Warray-bounds complained about > > strncpy() being used against an empty object. It turns out this was due to > > the at25 allocation going missing during a conflict resolution. Restore > > this, and while we're here take the opportunity to do another strncpy() > > replacement, since it's use is deprecated[1]. > > > > Seen as: > > > > In function 'strncpy', > > inlined from 'at25_fw_to_chip.constprop' at drivers/misc/eeprom/at25.c:312:2: > > ./include/linux/fortify-string.h:48:33: warning: '__builtin_strncpy' offset [0, 9] is out of the bounds [0, 0] [-Warray-bounds] > > 48 | #define __underlying_strncpy __builtin_strncpy > > | ^ > > ./include/linux/fortify-string.h:59:16: note: in expansion of macro '__underlying_strncpy' > > 59 | return __underlying_strncpy(p, q, size); > > | ^~~~~~~~~~~~~~~~~~~~ > > In function 'strncpy', > > inlined from 'at25_fram_to_chip' at drivers/misc/eeprom/at25.c:373:2, > > inlined from 'at25_probe' at drivers/misc/eeprom/at25.c:453:10: > > ./include/linux/fortify-string.h:48:33: warning: '__builtin_strncpy' offset [0, 9] is out of the bounds [0, 0] [-Warray-bounds] > > 48 | #define __underlying_strncpy __builtin_strncpy > > | ^ > > ./include/linux/fortify-string.h:59:16: note: in expansion of macro '__underlying_strncpy' > > 59 | return __underlying_strncpy(p, q, size); > > | ^~~~~~~~~~~~~~~~~~~~ > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings > > Thanks! > With or without the below comment being addressed > Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com> Thanks! > > > Fixes: af40d16042d6 ("Merge v5.15-rc5 into char-misc-next") > > Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> > > Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> > > Cc: Arnd Bergmann <arnd@...db.de> > > Cc: Jiri Prchal <jiri.prchal@...ignal.cz> > > Signed-off-by: Kees Cook <keescook@...omium.org> > > --- > > drivers/misc/eeprom/at25.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c > > index c3305bdda69c..1a19fa5728c8 100644 > > --- a/drivers/misc/eeprom/at25.c > > +++ b/drivers/misc/eeprom/at25.c > > @@ -309,7 +309,7 @@ static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip) > > u32 val; > > int err; > > > > - strncpy(chip->name, "at25", sizeof(chip->name)); > > + strscpy(chip->name, "at25", sizeof(chip->name)); > > > > err = device_property_read_u32(dev, "size", &val); > > if (err) > > @@ -370,7 +370,7 @@ static int at25_fram_to_chip(struct device *dev, struct spi_eeprom *chip) > > u8 id[FM25_ID_LEN]; > > int i; > > > > - strncpy(chip->name, "fm25", sizeof(chip->name)); > > + strscpy(chip->name, "fm25", sizeof(chip->name)); > > > > /* Get ID of chip */ > > fm25_aux_read(at25, id, FM25_RDID, FM25_ID_LEN); > > @@ -440,6 +440,10 @@ static int at25_probe(struct spi_device *spi) > > return -ENXIO; > > } > > > > + at25 = devm_kzalloc(&spi->dev, sizeof(struct at25_data), GFP_KERNEL); > > I would use sizeof(*at25) but I think you restored the exact context. Yeah, I just restore the chunk exactly as it was. Greg, should I send a v2 with this adjusted? -Kees > > > + if (!at25) > > + return -ENOMEM; > > + > > mutex_init(&at25->lock); > > at25->spi = spi; > > spi_set_drvdata(spi, at25); > > -- > > 2.30.2 > > > > > -- > With Best Regards, > Andy Shevchenko -- Kees Cook
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