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| author | Cyril Hrubis <chrubis@suse.cz> | 2024-02-22 18:05:40 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-03-01 13:06:08 +0100 |
| commit | 2d931472d4740d3ada7011cc4c3499948d3a22fa (patch) | |
| tree | 6dc77ce7b1f8b6914a14b9e974f0d9b4647862fb /kernel | |
| parent | 1f80bc015277247c9fd9646f7c21f1c728b5d908 (diff) | |
| download | linux-stable-2d931472d4740d3ada7011cc4c3499948d3a22fa.tar.gz linux-stable-2d931472d4740d3ada7011cc4c3499948d3a22fa.tar.bz2 linux-stable-2d931472d4740d3ada7011cc4c3499948d3a22fa.zip | |
sched/rt: Disallow writing invalid values to sched_rt_period_us
[ 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@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
[ 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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/rt.c | 5 | ||||
| -rw-r--r-- | kernel/sysctl.c | 5 |
2 files changed, 6 insertions, 4 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 2ea4da8c5f3a..deb9366e4f30 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2658,9 +2658,6 @@ 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; @@ -2690,7 +2687,7 @@ 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 4bb194f096ec..6ce9f10b9c7d 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -127,6 +127,7 @@ static int zero; static int __maybe_unused one = 1; static int __maybe_unused two = 2; static int __maybe_unused four = 4; +static int int_max = INT_MAX; static unsigned long zero_ul; static unsigned long one_ul = 1; static unsigned long long_max = LONG_MAX; @@ -464,6 +465,8 @@ 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", @@ -471,6 +474,8 @@ 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", |