From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Thu, 09 Jul 2020 10:48:18 +0000 Subject: [PATCH] kernel/smp: Fix an off by one in csd_lock_wait_toolong() Message-Id: <20200709104818.GC20875@mwanda> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: Ingo Molnar , Thomas Gleixner , Sebastian Andrzej Siewior , "Paul E. McKenney" , Kaitao Cheng , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org The __per_cpu_offset[] array has "nr_cpu_ids" elements so change the > >= to prevent a read one element beyond the end of the array. Fixes: 0504bc41a62c ("kernel/smp: Provide CSD lock timeout diagnostics") Signed-off-by: Dan Carpenter --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index 78b602cae6c2..f49966713ac3 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -171,7 +171,7 @@ static __always_inline bool csd_lock_wait_toolong(call_single_data_t *csd, u64 t *bug_id = atomic_inc_return(&csd_bug_count); cpu = csd_lock_wait_getcpu(csd); smp_mb(); // No stale cur_csd values! - if (WARN_ONCE(cpu < 0 || cpu > nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu)) + if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu)) cpu_cur_csd = READ_ONCE(per_cpu(cur_csd, 0)); else cpu_cur_csd = READ_ONCE(per_cpu(cur_csd, cpu)); -- 2.27.0