--- /dev/null
+From 079be8fc630943d9fc70a97807feb73d169ee3fc Mon Sep 17 00:00:00 2001
+From: Cyril Hrubis <chrubis@suse.cz>
+Date: Mon, 2 Oct 2023 13:55:51 +0200
+Subject: sched/rt: Disallow writing invalid values to sched_rt_period_us
+
+From: Cyril Hrubis <chrubis@suse.cz>
+
+commit 079be8fc630943d9fc70a97807feb73d169ee3fc upstream.
+
+The validation of the value written to sched_rt_period_us was broken
+because:
+
+ - the sysclt_sched_rt_period is declared as unsigned int
+ - parsed by proc_do_intvec()
+ - the range is asserted after the value parsed by proc_do_intvec()
+
+Because of this negative values written to the file were written into a
+unsigned integer that were later on interpreted as large positive
+integers which did passed the check:
+
+ if (sysclt_sched_rt_period <= 0)
+ return EINVAL;
+
+This commit fixes the parsing by setting explicit range for both
+perid_us and runtime_us into the sched_rt_sysctls table and processes
+the values with proc_dointvec_minmax() instead.
+
+Alternatively if we wanted to use full range of unsigned int for the
+period value we would have to split the proc_handler and use
+proc_douintvec() for it however even the
+Documentation/scheduller/sched-rt-group.rst describes the range as 1 to
+INT_MAX.
+
+As far as I can tell the only problem this causes is that the sysctl
+file allows writing negative values which when read back may confuse
+userspace.
+
+There is also a LTP test being submitted for these sysctl files at:
+
+ http://patchwork.ozlabs.org/project/ltp/patch/20230901144433.2526-1-chrubis@suse.cz/
+
+Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Link: https://lore.kernel.org/r/20231002115553.3007-2-chrubis@suse.cz
+Cc: Mahmoud Adam <mngyadam@amazon.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/rt.c | 9 +++++----
+ 1 file changed, 5 insertions(+), 4 deletions(-)
+
+--- a/kernel/sched/rt.c
++++ b/kernel/sched/rt.c
+@@ -37,6 +37,8 @@ static struct ctl_table sched_rt_sysctls
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = sched_rt_handler,
++ .extra1 = SYSCTL_ONE,
++ .extra2 = SYSCTL_INT_MAX,
+ },
+ {
+ .procname = "sched_rt_runtime_us",
+@@ -44,6 +46,8 @@ static struct ctl_table sched_rt_sysctls
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sched_rt_handler,
++ .extra1 = SYSCTL_NEG_ONE,
++ .extra2 = SYSCTL_INT_MAX,
+ },
+ {
+ .procname = "sched_rr_timeslice_ms",
+@@ -2970,9 +2974,6 @@ static int sched_rt_global_constraints(v
+ #ifdef CONFIG_SYSCTL
+ static int sched_rt_global_validate(void)
+ {
+- if (sysctl_sched_rt_period <= 0)
+- return -EINVAL;
+-
+ if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
+ ((sysctl_sched_rt_runtime > sysctl_sched_rt_period) ||
+ ((u64)sysctl_sched_rt_runtime *
+@@ -3003,7 +3004,7 @@ static int sched_rt_handler(struct ctl_t
+ old_period = sysctl_sched_rt_period;
+ old_runtime = sysctl_sched_rt_runtime;
+
+- ret = proc_dointvec(table, write, buffer, lenp, ppos);
++ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+ if (!ret && write) {
+ ret = sched_rt_global_validate();
--- /dev/null
+From c1fc6484e1fb7cc2481d169bfef129a1b0676abe Mon Sep 17 00:00:00 2001
+From: Cyril Hrubis <chrubis@suse.cz>
+Date: Wed, 2 Aug 2023 17:19:06 +0200
+Subject: sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset
+
+From: Cyril Hrubis <chrubis@suse.cz>
+
+commit c1fc6484e1fb7cc2481d169bfef129a1b0676abe upstream.
+
+The sched_rr_timeslice can be reset to default by writing value that is
+<= 0. However after reading from this file we always got the last value
+written, which is not useful at all.
+
+$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
+$ cat /proc/sys/kernel/sched_rr_timeslice_ms
+-1
+
+Fix this by setting the variable that holds the sysctl file value to the
+jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.
+
+Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Reviewed-by: Petr Vorel <pvorel@suse.cz>
+Acked-by: Mel Gorman <mgorman@suse.de>
+Tested-by: Petr Vorel <pvorel@suse.cz>
+Cc: Mahmoud Adam <mngyadam@amazon.com>
+Link: https://lore.kernel.org/r/20230802151906.25258-3-chrubis@suse.cz
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/rt.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/kernel/sched/rt.c
++++ b/kernel/sched/rt.c
+@@ -3048,6 +3048,9 @@ static int sched_rr_handler(struct ctl_t
+ sched_rr_timeslice =
+ sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
+ msecs_to_jiffies(sysctl_sched_rr_timeslice);
++
++ if (sysctl_sched_rr_timeslice <= 0)
++ sysctl_sched_rr_timeslice = jiffies_to_msecs(RR_TIMESLICE);
+ }
+ mutex_unlock(&mutex);
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
