Messages in this thread | | | Subject | Re: [PATCH v2 5/5] ucounts: Handle wrapping in is_ucounts_overlimit | From | Shuah Khan <> | Date | Wed, 16 Feb 2022 10:28:35 -0700 |
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On 2/16/22 8:58 AM, Eric W. Biederman wrote: > While examining is_ucounts_overlimit and reading the various messages > I realized that is_ucounts_overlimit fails to deal with counts that > may have wrapped. > > Being wrapped should be a transitory state for counts and they should > never be wrapped for long, but it can happen so handle it. > > Cc: stable@vger.kernel.org > Fixes: 21d1c5e386bc ("Reimplement RLIMIT_NPROC on top of ucounts") > Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> > --- > kernel/ucount.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/ucount.c b/kernel/ucount.c > index 65b597431c86..06ea04d44685 100644 > --- a/kernel/ucount.c > +++ b/kernel/ucount.c > @@ -350,7 +350,8 @@ bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsign > if (rlimit > LONG_MAX) > max = LONG_MAX; > for (iter = ucounts; iter; iter = iter->ns->ucounts) { > - if (get_ucounts_value(iter, type) > max) > + long val = get_ucounts_value(iter, type); > + if (val < 0 || val > max) > return true; > max = READ_ONCE(iter->ns->ucount_max[type]); > } >
This addresses the concerns about overflow.
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
thanks, -- Shuah
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