From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Khlebnikov Subject: [PATCH] sched/core: check format and overflows in cgroup2 cpu.max Date: Wed, 27 Feb 2019 11:13:21 +0300 Message-ID: <155125520155.293746.7017401430432481979.stgit@buzz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1551255202; bh=8kFu2wWh3Op+B8NZK/FPFrEnAAthfynrTJBN0YQ9dko=; h=Message-ID:Date:To:From:Subject; b=QChFQyWQRPml22HfRer0LqfEssiFGUcpS1KWe5R0TIdlZuGFWNRKKj56z9MhhdZXt Zd+DrubbdYyyqGmvyngmLnkwfAP4CcG/3cAK5wAtuyqVojB77JYtHHqk4pYxpRMr0x cHn31V4Ku8OwHCDGPQQjuQSDXj2R6508Qb/v2HBk= Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Peter Zijlstra , linux-kernel@vger.kernel.org, Li Zefan , Johannes Weiner , Tejun Heo , cgroups@vger.kernel.org, Ingo Molnar Cgroup2 interface for cpu bandwidth limit has some flaws: - on stack buffer overflow - no checks for valid format or trailing garbage - no checks for integer overflows This patch fixes all these flaws. Fixes: 0d5936344f30 ("sched: Implement interface for cgroup unified hierarchy") Signed-off-by: Konstantin Khlebnikov --- kernel/sched/core.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5f46aa335b28..123b1910bc2e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6947,19 +6947,34 @@ static int __maybe_unused cpu_period_quota_parse(char *buf, u64 *periodp, u64 *quotap) { char tok[21]; /* U64_MAX */ + int ret, len; - if (!sscanf(buf, "%s %llu", tok, periodp)) + if (sscanf(buf, "%20s %n", tok, &len) != 1) return -EINVAL; - *periodp *= NSEC_PER_USEC; - - if (sscanf(tok, "%llu", quotap)) - *quotap *= NSEC_PER_USEC; - else if (!strcmp(tok, "max")) + ret = kstrtou64(tok, 10, quotap); + if (ret) { + if (strcmp(tok, "max")) + return ret; *quotap = RUNTIME_INF; - else + } else if (*quotap <= U64_MAX / NSEC_PER_USEC) { + *quotap *= NSEC_PER_USEC; + } else return -EINVAL; + buf += len; + if (*buf) { + if (sscanf(buf, "%20s %n", tok, &len) != 1 || buf[len]) + return -EINVAL; + ret = kstrtou64(tok, 10, periodp); + if (ret) + return ret; + if (*periodp > U64_MAX / NSEC_PER_USEC) + return -EINVAL; + } + + *periodp *= NSEC_PER_USEC; + return 0; }