linux-kernel - [PATCH] clk: tegra: Fix an infinite loop when clock rate is zero

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180921220037.16862-1-decatf@gmail.com>
Date:   Fri, 21 Sep 2018 18:00:37 -0400
From:   ryang <decatf@...il.com>
To:     Peter De Schrijver <pdeschrijver@...dia.com>
Cc:     Prashant Gaikwad <pgaikwad@...dia.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-clk@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, ryang <decatf@...il.com>
Subject: [PATCH] clk: tegra: Fix an infinite loop when clock rate is zero

Calling clk_set_rate or clk_round_rate will lock up the kernel when the
rate is zero. This avoids the infinite loop and uses a slightly more
optimized p divider calculation.

Signed-off-by: ryang <decatf@...il.com>
---
 drivers/clk/tegra/clk-pll.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c
index 830d1c87fa7c..17a058c3bbc1 100644
--- a/drivers/clk/tegra/clk-pll.c
+++ b/drivers/clk/tegra/clk-pll.c
@@ -582,9 +582,8 @@ static int _calc_rate(struct clk_hw *hw, struct tegra_clk_pll_freq_table *cfg,
 	}
 
 	/* Raise VCO to guarantee 0.5% accuracy */
-	for (cfg->output_rate = rate; cfg->output_rate < 200 * cfreq;
-	     cfg->output_rate <<= 1)
-		p_div++;
+	p_div = rate ? fls((200 * cfreq) / rate) : 0;
+	cfg->output_rate = rate << p_div;
 
 	cfg->m = parent_rate / cfreq;
 	cfg->n = cfg->output_rate / cfreq;
-- 
2.17.1