6.15-stable review patch. If anyone has any objections, please let me know.
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From: Artem Sadovnikov a.sadovnikov@ispras.ru
[ Upstream commit 005b6187705bc9723518ce19c5cb911fc1f7ef07 ]
The nreaders and loops variables are exposed as module parameters, which, in certain combinations, can lead to multiplication overflow.
Besides, loops parameter is defined as long, while through the code is used as int, which can cause truncation on 64-bit kernels and possible zeroes where they shouldn't appear.
Since code uses result of multiplication as int anyway, it only makes sense to replace loops with int. Multiplication overflow check is also added due to possible multiplication between two very big numbers.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 653ed64b01dc ("refperf: Add a test to measure performance of read-side synchronization") Signed-off-by: Artem Sadovnikov a.sadovnikov@ispras.ru Signed-off-by: Neeraj Upadhyay (AMD) neeraj.upadhyay@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/rcu/refscale.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index f11a7c2af778..ab7fcdc94cc0 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -85,7 +85,7 @@ torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0, // Number of typesafe_lookup structures, that is, the degree of concurrency. torture_param(long, lookup_instances, 0, "Number of typesafe_lookup structures."); // Number of loops per experiment, all readers execute operations concurrently. -torture_param(long, loops, 10000, "Number of loops per experiment."); +torture_param(int, loops, 10000, "Number of loops per experiment."); // Number of readers, with -1 defaulting to about 75% of the CPUs. torture_param(int, nreaders, -1, "Number of readers, -1 for 75% of CPUs."); // Number of runs. @@ -1140,7 +1140,7 @@ static void ref_scale_print_module_parms(const struct ref_scale_ops *cur_ops, const char *tag) { pr_alert("%s" SCALE_FLAG - "--- %s: verbose=%d verbose_batched=%d shutdown=%d holdoff=%d lookup_instances=%ld loops=%ld nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag, + "--- %s: verbose=%d verbose_batched=%d shutdown=%d holdoff=%d lookup_instances=%ld loops=%d nreaders=%d nruns=%d readdelay=%d\n", scale_type, tag, verbose, verbose_batched, shutdown, holdoff, lookup_instances, loops, nreaders, nruns, readdelay); }
@@ -1238,12 +1238,16 @@ ref_scale_init(void) // Reader tasks (default to ~75% of online CPUs). if (nreaders < 0) nreaders = (num_online_cpus() >> 1) + (num_online_cpus() >> 2); - if (WARN_ONCE(loops <= 0, "%s: loops = %ld, adjusted to 1\n", __func__, loops)) + if (WARN_ONCE(loops <= 0, "%s: loops = %d, adjusted to 1\n", __func__, loops)) loops = 1; if (WARN_ONCE(nreaders <= 0, "%s: nreaders = %d, adjusted to 1\n", __func__, nreaders)) nreaders = 1; if (WARN_ONCE(nruns <= 0, "%s: nruns = %d, adjusted to 1\n", __func__, nruns)) nruns = 1; + if (WARN_ONCE(loops > INT_MAX / nreaders, + "%s: nreaders * loops will overflow, adjusted loops to %d", + __func__, INT_MAX / nreaders)) + loops = INT_MAX / nreaders; reader_tasks = kcalloc(nreaders, sizeof(reader_tasks[0]), GFP_KERNEL); if (!reader_tasks) {