On 5/20/20 12:56 PM, kbuild test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > head: fb57b1fabcb28f358901b2df90abd2b48abc1ca8 > commit: 0e19fc1c40bd7516d5a30a459db4f49d48910847 [10679/10701] mm: consolidate pgd_index() and pgd_offset{_k}() definitions > config: i386-randconfig-a005-20200520 (attached as .config) > compiler: gcc-4.9 (Ubuntu 4.9.3-13ubuntu2) 4.9.3 > reproduce: > git checkout 0e19fc1c40bd7516d5a30a459db4f49d48910847 > # save the attached .config to linux build tree > make ARCH=i386 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kbuild test robot <lkp@xxxxxxxxx> > > All warnings (new ones prefixed by >>, old ones prefixed by <<): > > arch/x86/mm/pgtable.c: In function 'pgd_alloc': >>> arch/x86/mm/pgtable.c:427:2: warning: variable length array 'u_pmds' is used [-Wvla] > pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS]; > ^ >>> arch/x86/mm/pgtable.c:428:2: warning: variable length array 'pmds' is used [-Wvla] > pmd_t *pmds[MAX_PREALLOCATED_PMDS]; > ^ > Yes, I also reported this on linux-next of 20200518 (but I didn't copy Mike on it). > vim +/u_pmds +427 arch/x86/mm/pgtable.c > > 1db491f77b6ed0 Fenghua Yu 2015-01-15 423 > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 424 pgd_t *pgd_alloc(struct mm_struct *mm) > 1ec1fe73dfb711 Ingo Molnar 2008-03-19 425 { > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 426 pgd_t *pgd; > 184d47f0fd3651 Kees Cook 2018-10-08 @427 pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS]; > 184d47f0fd3651 Kees Cook 2018-10-08 @428 pmd_t *pmds[MAX_PREALLOCATED_PMDS]; > 1ec1fe73dfb711 Ingo Molnar 2008-03-19 429 > 1db491f77b6ed0 Fenghua Yu 2015-01-15 430 pgd = _pgd_alloc(); > 1ec1fe73dfb711 Ingo Molnar 2008-03-19 431 > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 432 if (pgd == NULL) > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 433 goto out; > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 434 > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 435 mm->pgd = pgd; > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 436 > f59dbe9ca6707e Joerg Roedel 2018-07-18 437 if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0) > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 438 goto out_free_pgd; > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 439 > f59dbe9ca6707e Joerg Roedel 2018-07-18 440 if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0) > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 441 goto out_free_pmds; > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 442 > f59dbe9ca6707e Joerg Roedel 2018-07-18 443 if (paravirt_pgd_alloc(mm) != 0) > f59dbe9ca6707e Joerg Roedel 2018-07-18 444 goto out_free_user_pmds; > f59dbe9ca6707e Joerg Roedel 2018-07-18 445 > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 446 /* > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 447 * Make sure that pre-populating the pmds is atomic with > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 448 * respect to anything walking the pgd_list, so that they > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 449 * never see a partially populated pgd. > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 450 */ > a79e53d85683c6 Andrea Arcangeli 2011-02-16 451 spin_lock(&pgd_lock); > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 452 > 617d34d9e5d832 Jeremy Fitzhardinge 2010-09-21 453 pgd_ctor(mm, pgd); > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 454 pgd_prepopulate_pmd(mm, pgd, pmds); > f59dbe9ca6707e Joerg Roedel 2018-07-18 455 pgd_prepopulate_user_pmd(mm, pgd, u_pmds); > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 456 > a79e53d85683c6 Andrea Arcangeli 2011-02-16 457 spin_unlock(&pgd_lock); > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 458 > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 459 return pgd; > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 460 > f59dbe9ca6707e Joerg Roedel 2018-07-18 461 out_free_user_pmds: > f59dbe9ca6707e Joerg Roedel 2018-07-18 462 free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS); > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 463 out_free_pmds: > f59dbe9ca6707e Joerg Roedel 2018-07-18 464 free_pmds(mm, pmds, PREALLOCATED_PMDS); > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 465 out_free_pgd: > 1db491f77b6ed0 Fenghua Yu 2015-01-15 466 _pgd_free(pgd); > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 467 out: > d8d5900ef8afc5 Jeremy Fitzhardinge 2008-06-25 468 return NULL; > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 469 } > 4f76cd382213b2 Jeremy Fitzhardinge 2008-03-17 470 > > :::::: The code at line 427 was first introduced by commit > :::::: 184d47f0fd365108bd06ab26cdb3450b716269fd x86/mm: Avoid VLA in pgd_alloc() > > :::::: TO: Kees Cook <keescook@xxxxxxxxxxxx> > :::::: CC: Ingo Molnar <mingo@xxxxxxxxxx> > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx > -- ~Randy Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
