From: Dan Carpenter Date: Thu, 1 Aug 2024 15:44:03 +0000 (-0500) Subject: sched/debug: Fix fair_server_period_max value X-Git-Tag: v6.12-rc1~120^2~47 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4ae0c2b91110dab6f4291c2c7f99dde60ecc97d8;p=thirdparty%2Fkernel%2Flinux.git sched/debug: Fix fair_server_period_max value This code has an integer overflow or sign extension bug which was caught by gcc-13: kernel/sched/debug.c:341:57: error: integer overflow in expression of type 'long int' results in '-100663296' [-Werror=overflow] 341 | static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */ The result is that "fair_server_period_max" is set to 0xfffffffffa000000 (585 years) instead of instead of 0xfa000000 (4 seconds) that was intended. Fix this by changing the type to shift from (1 << 22) to (1UL << 22). Closes: https://lore.kernel.org/all/CA+G9fYtE2GAbeqU+AOCffgo2oH0RTJUxU+=Pi3cFn4di_KgBAQ@mail.gmail.com/ Fixes: d741f297bcea ("sched/fair: Fair server interface") Reported-by: Linux Kernel Functional Testing Reported-by: Arnd Bergmann Reported-by: Stephen Rothwell Signed-off-by: Dan Carpenter Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/a936b991-e464-4bdf-94ab-08e25d364986@stanley.mountain --- diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index e75914e7d2a8c..831a77ab84661 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -338,7 +338,7 @@ enum dl_param { DL_PERIOD, }; -static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */ +static unsigned long fair_server_period_max = (1UL << 22) * NSEC_PER_USEC; /* ~4 seconds */ static unsigned long fair_server_period_min = (100) * NSEC_PER_USEC; /* 100 us */ static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubuf,