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SubjectRe: [kbuild] [ammarfaizi2-block:paulmck/linux-rcu/dev 80/83] kernel/rcu/srcutree.c:1426 srcu_torture_stats_print() error: buffer overflow 'srcu_size_state_name' 10 <= 10
On Wed, Jan 26, 2022 at 10:35:36AM +0300, Dan Carpenter wrote:
> tree: https://github.com/ammarfaizi2/linux-block paulmck/linux-rcu/dev
> head: 1063f4620dd3242633b35487e08e159b803f717b
> commit: 6d5d02daa5c0173da1c5430352dca9ab3f4fd8b5 [80/83] srcu: Make rcutorture dump the SRCU size state
> config: x86_64-randconfig-m001-20220124 (https://download.01.org/0day-ci/archive/20220126/202201261439.SqXHa4LN-lkp@intel.com/config )
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> smatch warnings:
> kernel/rcu/srcutree.c:1426 srcu_torture_stats_print() error: buffer overflow 'srcu_size_state_name' 10 <= 10
>
> vim +/srcu_size_state_name +1426 kernel/rcu/srcutree.c
>
> aacb5d91ab1bfb Paul E. McKenney 2018-10-28 1415 void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf)
> 115a1a5285664f Paul E. McKenney 2017-05-22 1416 {
> 115a1a5285664f Paul E. McKenney 2017-05-22 1417 int cpu;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1418 int idx;
> ac3748c6042660 Paul E. McKenney 2017-05-22 1419 unsigned long s0 = 0, s1 = 0;
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1420 int ss_state = READ_ONCE(ssp->srcu_size_state);
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1421 int ss_state_idx = ss_state;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1422
> aacb5d91ab1bfb Paul E. McKenney 2018-10-28 1423 idx = ssp->srcu_idx & 0x1;
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1424 if (ss_state < 0 || ss_state >= ARRAY_SIZE(srcu_size_state_name))
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1425 ss_state_idx = ARRAY_SIZE(srcu_size_state_name);
>
> This was supposed to be ss_state_idx = ARRAY_SIZE(srcu_size_state_name) - 1;

Good catch! Fixed, and will merge into original commit with
attribution, thank you!

Thanx, Paul

> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 @1426 pr_alert("%s%s Tree SRCU g%ld state %d (%s) per-CPU(idx=%d):",
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1427 tt, tf, rcu_seq_current(&ssp->srcu_gp_seq), ss_state,
> 6d5d02daa5c017 Paul E. McKenney 2022-01-24 1428 srcu_size_state_name[ss_state_idx], idx);
> 115a1a5285664f Paul E. McKenney 2017-05-22 1429 for_each_possible_cpu(cpu) {
> 115a1a5285664f Paul E. McKenney 2017-05-22 1430 unsigned long l0, l1;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1431 unsigned long u0, u1;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1432 long c0, c1;
> 5ab07a8df4d6c9 Paul E. McKenney 2018-05-22 1433 struct srcu_data *sdp;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1434
> aacb5d91ab1bfb Paul E. McKenney 2018-10-28 1435 sdp = per_cpu_ptr(ssp->sda, cpu);
> b68c6146512d92 Paul E. McKenney 2020-01-03 1436 u0 = data_race(sdp->srcu_unlock_count[!idx]);
> b68c6146512d92 Paul E. McKenney 2020-01-03 1437 u1 = data_race(sdp->srcu_unlock_count[idx]);
> 115a1a5285664f Paul E. McKenney 2017-05-22 1438
> 115a1a5285664f Paul E. McKenney 2017-05-22 1439 /*
> 115a1a5285664f Paul E. McKenney 2017-05-22 1440 * Make sure that a lock is always counted if the corresponding
> 115a1a5285664f Paul E. McKenney 2017-05-22 1441 * unlock is counted.
> 115a1a5285664f Paul E. McKenney 2017-05-22 1442 */
> 115a1a5285664f Paul E. McKenney 2017-05-22 1443 smp_rmb();
> 115a1a5285664f Paul E. McKenney 2017-05-22 1444
> b68c6146512d92 Paul E. McKenney 2020-01-03 1445 l0 = data_race(sdp->srcu_lock_count[!idx]);
> b68c6146512d92 Paul E. McKenney 2020-01-03 1446 l1 = data_race(sdp->srcu_lock_count[idx]);
> 115a1a5285664f Paul E. McKenney 2017-05-22 1447
> 115a1a5285664f Paul E. McKenney 2017-05-22 1448 c0 = l0 - u0;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1449 c1 = l1 - u1;
> 7e210a653ec944 Paul E. McKenney 2019-06-28 1450 pr_cont(" %d(%ld,%ld %c)",
> 7e210a653ec944 Paul E. McKenney 2019-06-28 1451 cpu, c0, c1,
> 7e210a653ec944 Paul E. McKenney 2019-06-28 1452 "C."[rcu_segcblist_empty(&sdp->srcu_cblist)]);
> ac3748c6042660 Paul E. McKenney 2017-05-22 1453 s0 += c0;
> ac3748c6042660 Paul E. McKenney 2017-05-22 1454 s1 += c1;
> 115a1a5285664f Paul E. McKenney 2017-05-22 1455 }
> ac3748c6042660 Paul E. McKenney 2017-05-22 1456 pr_cont(" T(%ld,%ld)\n", s0, s1);
> e3ec4a4e8733d5 Paul E. McKenney 2022-01-24 1457 smp_store_release(&ssp->srcu_size_state, SRCU_SIZE_ALLOC); // @@@
> 115a1a5285664f Paul E. McKenney 2017-05-22 1458 }
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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