From 475b92f932168a78da8109acd10bfb7578b8f2bb Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 14 Jun 2021 15:24:05 -0700 Subject: ptp: improve max_adj check against unreasonable values Scaled PPM conversion to PPB may (on 64bit systems) result in a value larger than s32 can hold (freq/scaled_ppm is a long). This means the kernel will not correctly reject unreasonably high ->freq values (e.g. > 4294967295ppb, 281474976645 scaled PPM). The conversion is equivalent to a division by ~66 (65.536), so the value of ppb is always smaller than ppm, but not small enough to assume narrowing the type from long -> s32 is okay. Note that reasonable user space (e.g. ptp4l) will not use such high values, anyway, 4289046510ppb ~= 4.3x, so the fix is somewhat pedantic. Fixes: d39a743511cd ("ptp: validate the requested frequency adjustment.") Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.") Signed-off-by: Jakub Kicinski Acked-by: Richard Cochran Signed-off-by: David S. Miller --- include/linux/ptp_clock_kernel.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/ptp_clock_kernel.h') diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index 0d47fd33b228..51d7f1b8b32a 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -235,7 +235,7 @@ extern int ptp_clock_index(struct ptp_clock *ptp); * @ppm: Parts per million, but with a 16 bit binary fractional field */ -extern s32 scaled_ppm_to_ppb(long ppm); +extern long scaled_ppm_to_ppb(long ppm); /** * ptp_find_pin() - obtain the pin index of a given auxiliary function -- cgit v1.2.3