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authorJakub Kicinski <kuba@kernel.org>2021-06-14 15:24:05 -0700
committerDavid S. Miller <davem@davemloft.net>2021-06-15 10:59:46 -0700
commit475b92f932168a78da8109acd10bfb7578b8f2bb (patch)
tree1659ca2f045d8cc6295dae645c844e3228326494 /drivers/ptp
parent2214fb53006e6cfa6371b706070cb99794c68c3b (diff)
downloadlinux-475b92f932168a78da8109acd10bfb7578b8f2bb.tar.bz2
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 <kuba@kernel.org> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/ptp')
-rw-r--r--drivers/ptp/ptp_clock.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 03a246e60fd9..21c4c34c52d8 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -63,7 +63,7 @@ static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
spin_unlock_irqrestore(&queue->lock, flags);
}
-s32 scaled_ppm_to_ppb(long ppm)
+long scaled_ppm_to_ppb(long ppm)
{
/*
* The 'freq' field in the 'struct timex' is in parts per
@@ -80,7 +80,7 @@ s32 scaled_ppm_to_ppb(long ppm)
s64 ppb = 1 + ppm;
ppb *= 125;
ppb >>= 13;
- return (s32) ppb;
+ return (long) ppb;
}
EXPORT_SYMBOL(scaled_ppm_to_ppb);
@@ -138,7 +138,7 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
delta = ktime_to_ns(kt);
err = ops->adjtime(ops, delta);
} else if (tx->modes & ADJ_FREQUENCY) {
- s32 ppb = scaled_ppm_to_ppb(tx->freq);
+ long ppb = scaled_ppm_to_ppb(tx->freq);
if (ppb > ops->max_adj || ppb < -ops->max_adj)
return -ERANGE;
if (ops->adjfine)