From 3c0cf801ea2fa40daa5e7d1e6d32adca5ff75ad9 Mon Sep 17 00:00:00 2001 From: Linmao Li Date: Thu, 16 Jul 2026 09:39:23 +0800 Subject: [PATCH] ppdev: prevent overflow when setting port timeout PPSETTIME64 supplies the timeval fields as s64 values, but pp_set_timeout() narrows tv_usec to int and calculates tv_sec * HZ in a signed long. Large positive values can therefore be truncated or overflow and install an unintended timeout. Keep both fields as s64, reject a non-canonical microsecond value, and use timespec64_to_jiffies() to cap excessively large timeouts at MAX_JIFFY_OFFSET. This is a behavior change because both PPSETTIME ioctls could previously accept values with tv_usec >= USEC_PER_SEC. The validation follows the precedent set by sock_set_timeout(). Fixes: 3b9ab374a1e6 ("ppdev: convert to y2038 safe") Signed-off-by: Linmao Li Reviewed-by: Arnd Bergmann Link: https://patch.msgid.link/20260716013923.19494-1-lilinmao@kylinos.cn Signed-off-by: Greg Kroah-Hartman --- drivers/char/ppdev.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c index 6da817b9849f..8803268b4cdc 100644 --- a/drivers/char/ppdev.c +++ b/drivers/char/ppdev.c @@ -340,15 +340,17 @@ static enum ieee1284_phase init_phase(int mode) return IEEE1284_PH_FWD_IDLE; } -static int pp_set_timeout(struct pardevice *pdev, long tv_sec, int tv_usec) +static int pp_set_timeout(struct pardevice *pdev, s64 tv_sec, s64 tv_usec) { + struct timespec64 ts; long to_jiffies; - if ((tv_sec < 0) || (tv_usec < 0)) + if (tv_sec < 0 || tv_usec < 0 || tv_usec >= USEC_PER_SEC) return -EINVAL; - to_jiffies = usecs_to_jiffies(tv_usec); - to_jiffies += tv_sec * HZ; + ts.tv_sec = tv_sec; + ts.tv_nsec = tv_usec * NSEC_PER_USEC; + to_jiffies = timespec64_to_jiffies(&ts); if (to_jiffies <= 0) return -EINVAL;