From: Cyril Hrubis chrubis@suse.cz

stable inclusion from stable-v4.19.308 commit 2d931472d4740d3ada7011cc4c3499948d3a22fa category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9K4JZ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=l...

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[ Upstream commit 079be8fc630943d9fc70a97807feb73d169ee3fc ]

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@...

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 [ pvorel: rebased for 4.19 ] Reviewed-by: Petr Vorel pvorel@suse.cz Signed-off-by: Petr Vorel pvorel@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

Conflicts: kernel/sysctl.c Signed-off-by: Cheng Yu serein.chengyu@huawei.com --- kernel/sched/rt.c | 5 +---- kernel/sysctl.c | 5 +++++ 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 5dff9a6fe2cf..724a31e0b2a3 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2655,9 +2655,6 @@ static int sched_rt_global_constraints(void)

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)) return -EINVAL; @@ -2687,7 +2684,7 @@ int sched_rt_handler(struct ctl_table *table, int write, 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(); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c7064f67f4a5..f64c4495bc54 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -131,6 +131,7 @@ static int __maybe_unused three = 3; static int __maybe_unused four = 4; static int __maybe_unused five = 5; static int __maybe_unused uce_kernel_recovery_max = 31; +static int int_max = INT_MAX; static unsigned long zero_ul; static unsigned long one_ul = 1; static unsigned long long_max = LONG_MAX; @@ -463,6 +464,8 @@ static struct ctl_table kern_table[] = { .maxlen = sizeof(unsigned int), .mode = 0644, .proc_handler = sched_rt_handler, + .extra1 = &one, + .extra2 = &int_max, }, { .procname = "sched_rt_runtime_us", @@ -470,6 +473,8 @@ static struct ctl_table kern_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = sched_rt_handler, + .extra1 = &neg_one, + .extra2 = &int_max, }, { .procname = "sched_rr_timeslice_ms",