From: Jonathan Cameron > Sent: 09 August 2021 10:22 > > On Sun, 8 Aug 2021 22:00:34 +0300 > Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > > On Sun, Aug 8, 2021 at 7:25 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > > > > > > On Sat, 7 Aug 2021 17:22:25 +0200 > > > Len Baker <len.baker@xxxxxxx> wrote: > > > > > > > strcpy() performs no bounds checking on the destination buffer. This > > > > could result in linear overflows beyond the end of the buffer, leading > > > > to all kinds of misbehaviors. The safe replacement is strscpy(). > > > > > > > > This patch is an effort to clean up the proliferation of str*() > > > > functions in the kernel and a previous step in the path to remove > > > > the strcpy function from the kernel entirely [1]. > > > > > > > > [1] https://github.com/KSPP/linux/issues/88 > > > > > > > > Signed-off-by: Len Baker <len.baker@xxxxxxx> > > > Applied to the togreg branch of iio.git and pushed out as testing > > > so 0-day can poke at it and see if we missed anything. > > > > Isn't it too early? Or am I missing something (see below)? > > > > ... > > > > > > /* use length + 2 for adding minus sign if needed */ > > > > - str = devm_kzalloc(regmap_get_device(st->map), > > > > - strlen(orient) + 2, GFP_KERNEL); > > > > + n = strlen(orient) + 2; > > > > + str = devm_kzalloc(regmap_get_device(st->map), n, > > > > + GFP_KERNEL); > > > > if (str == NULL) > > > > return -ENOMEM; > > > > if (strcmp(orient, "0") == 0) { > > > > - strcpy(str, orient); > > > > + strscpy(str, orient, n); > > > > } else if (orient[0] == '-') { > > > > - strcpy(str, &orient[1]); > > > > + strscpy(str, &orient[1], n); > > > > } else { > > > > str[0] = '-'; > > > > - strcpy(&str[1], orient); > > > > + strscpy(&str[1], orient, n - 1); > > > > Why n-1? > > n is the total length and this is printing from [1], so n - 1 is remaining > space. If you do: /* negate 'orient' */ n = strlen(orient) + 1; str = malloc(n + 1); if (n == 2 && orient[0] == '0') memcpy(str, orient, n); else if (orient[0] == '-') memcpy(str, orient + 1, n - 1); else { str[0] = '-'; memcpy(str + 1, orient, n); } Then it is probably less confusing. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
