On Wed, Jun 30, 2021 at 11:12 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > Hi Gabriel, > > url: https://github.com/0day-ci/linux/commits/Gabriel-Krisman-Bertazi/File-system-wide-monitoring/20210630-031347 > base: https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git fsnotify > config: x86_64-randconfig-m001-20210628 (attached as .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@xxxxxxxxx> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > > smatch warnings: > fs/notify/fsnotify.c:505 __fsnotify() warn: variable dereferenced before check 'inode' (see line 494) > > vim +/inode +505 fs/notify/fsnotify.c > > dca640915c7b84 Amir Goldstein 2021-06-29 470 int __fsnotify(__u32 mask, const struct fsnotify_event_info *event_info) > 90586523eb4b34 Eric Paris 2009-05-21 471 { > dca640915c7b84 Amir Goldstein 2021-06-29 472 const struct path *path = fsnotify_event_info_path(event_info); > dca640915c7b84 Amir Goldstein 2021-06-29 473 struct inode *inode = event_info->inode; > 3427ce71554123 Miklos Szeredi 2017-10-30 474 struct fsnotify_iter_info iter_info = {}; > 40a100d3adc1ad Amir Goldstein 2020-07-22 475 struct super_block *sb; > 60f7ed8c7c4d06 Amir Goldstein 2018-09-01 476 struct mount *mnt = NULL; > fecc4559780d52 Amir Goldstein 2020-12-02 477 struct inode *parent = NULL; > 9385a84d7e1f65 Jan Kara 2016-11-10 478 int ret = 0; > 71d734103edfa2 Mel Gorman 2020-07-08 479 __u32 test_mask, marks_mask; > 90586523eb4b34 Eric Paris 2009-05-21 480 > 71d734103edfa2 Mel Gorman 2020-07-08 481 if (path) > aa93bdc5500cc9 Amir Goldstein 2020-03-19 482 mnt = real_mount(path->mnt); > 3a9fb89f4cd04c Eric Paris 2009-12-17 483 > 40a100d3adc1ad Amir Goldstein 2020-07-22 484 if (!inode) { > 40a100d3adc1ad Amir Goldstein 2020-07-22 485 /* Dirent event - report on TYPE_INODE to dir */ > dca640915c7b84 Amir Goldstein 2021-06-29 486 inode = event_info->dir; > ^^^^^^^^^^^^^^^^^^^^^^^ > Presumably this is non-NULL > > 40a100d3adc1ad Amir Goldstein 2020-07-22 487 } else if (mask & FS_EVENT_ON_CHILD) { > 40a100d3adc1ad Amir Goldstein 2020-07-22 488 /* > fecc4559780d52 Amir Goldstein 2020-12-02 489 * Event on child - report on TYPE_PARENT to dir if it is > fecc4559780d52 Amir Goldstein 2020-12-02 490 * watching children and on TYPE_INODE to child. > 40a100d3adc1ad Amir Goldstein 2020-07-22 491 */ > dca640915c7b84 Amir Goldstein 2021-06-29 492 parent = event_info->dir; > 40a100d3adc1ad Amir Goldstein 2020-07-22 493 } > 40a100d3adc1ad Amir Goldstein 2020-07-22 @494 sb = inode->i_sb; > ^^^^^^^^^^^^ > Dereference > > 497b0c5a7c0688 Amir Goldstein 2020-07-16 495 > 7c49b8616460eb Dave Hansen 2015-09-04 496 /* > 7c49b8616460eb Dave Hansen 2015-09-04 497 * Optimization: srcu_read_lock() has a memory barrier which can > 7c49b8616460eb Dave Hansen 2015-09-04 498 * be expensive. It protects walking the *_fsnotify_marks lists. > 7c49b8616460eb Dave Hansen 2015-09-04 499 * However, if we do not walk the lists, we do not have to do > 7c49b8616460eb Dave Hansen 2015-09-04 500 * SRCU because we have no references to any objects and do not > 7c49b8616460eb Dave Hansen 2015-09-04 501 * need SRCU to keep them "alive". > 7c49b8616460eb Dave Hansen 2015-09-04 502 */ > 9b93f33105f5f9 Amir Goldstein 2020-07-16 503 if (!sb->s_fsnotify_marks && > 497b0c5a7c0688 Amir Goldstein 2020-07-16 504 (!mnt || !mnt->mnt_fsnotify_marks) && > 9b93f33105f5f9 Amir Goldstein 2020-07-16 @505 (!inode || !inode->i_fsnotify_marks) && > ^^^^^^ > Unnecessary check for NULL > > fecc4559780d52 Amir Goldstein 2020-12-02 506 (!parent || !parent->i_fsnotify_marks)) > 7c49b8616460eb Dave Hansen 2015-09-04 507 return 0; > 71d734103edfa2 Mel Gorman 2020-07-08 508 > 9b93f33105f5f9 Amir Goldstein 2020-07-16 509 marks_mask = sb->s_fsnotify_mask; > 71d734103edfa2 Mel Gorman 2020-07-08 510 if (mnt) > 71d734103edfa2 Mel Gorman 2020-07-08 511 marks_mask |= mnt->mnt_fsnotify_mask; > 9b93f33105f5f9 Amir Goldstein 2020-07-16 512 if (inode) > ^^^^^^ > > 9b93f33105f5f9 Amir Goldstein 2020-07-16 513 marks_mask |= inode->i_fsnotify_mask; > fecc4559780d52 Amir Goldstein 2020-12-02 514 if (parent) > fecc4559780d52 Amir Goldstein 2020-12-02 515 marks_mask |= parent->i_fsnotify_mask; > 497b0c5a7c0688 Amir Goldstein 2020-07-16 516 > 71d734103edfa2 Mel Gorman 2020-07-08 517 > 613a807fe7c793 Eric Paris 2010-07-28 518 /* > 613a807fe7c793 Eric Paris 2010-07-28 519 * if this is a modify event we may need to clear the ignored masks > 497b0c5a7c0688 Amir Goldstein 2020-07-16 520 * otherwise return if none of the marks care about this type of event. > 613a807fe7c793 Eric Paris 2010-07-28 521 */ > 71d734103edfa2 Mel Gorman 2020-07-08 522 test_mask = (mask & ALL_FSNOTIFY_EVENTS); > 71d734103edfa2 Mel Gorman 2020-07-08 523 if (!(mask & FS_MODIFY) && !(test_mask & marks_mask)) > 613a807fe7c793 Eric Paris 2010-07-28 524 return 0; > 75c1be487a690d Eric Paris 2010-07-28 525 > 9385a84d7e1f65 Jan Kara 2016-11-10 526 iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu); > 75c1be487a690d Eric Paris 2010-07-28 527 > 45a9fb3725d886 Amir Goldstein 2019-01-10 528 iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] = > 45a9fb3725d886 Amir Goldstein 2019-01-10 529 fsnotify_first_mark(&sb->s_fsnotify_marks); > 9bdda4e9cf2dce Amir Goldstein 2018-09-01 530 if (mnt) { > 47d9c7cc457adc Amir Goldstein 2018-04-20 531 iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] = > 3427ce71554123 Miklos Szeredi 2017-10-30 532 fsnotify_first_mark(&mnt->mnt_fsnotify_marks); > 7131485a93679f Eric Paris 2009-12-17 533 } > 9b93f33105f5f9 Amir Goldstein 2020-07-16 534 if (inode) { > ^^^^^ > Lots of checking... Maybe this is really NULL? Do you have feeling of dejavu? ;-) https://lore.kernel.org/linux-fsdevel/20200730192537.GB13525@xxxxxxxxxxxxxx/ We've been through this. Maybe you silenced the smach warning on fsnotify() and the rename to __fsnotifty() caused this warning to refloat? Thanks, Amir.
