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Date: Wed, 18 Oct 2023 16:54:33 +0800
From: Baoquan He <bhe@...hat.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: oe-kbuild@...ts.linux.dev, Lorenzo Stoakes <lstoakes@...il.com>,
lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: mm/vmalloc.c:3689 vread_iter() error: we previously assumed 'vm'
could be null (see line 3667)
Hi,
On 10/17/23 at 05:26pm, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 213f891525c222e8ed145ce1ce7ae1f47921cb9c
> commit: 4c91c07c93bbbdd7f2d9de2beb7ee5c2a48ad8e7 mm: vmalloc: convert vread() to vread_iter()
> config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20231017/202310171600.WCrsOwFj-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20231017/202310171600.WCrsOwFj-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> | Closes: https://lore.kernel.org/r/202310171600.WCrsOwFj-lkp@intel.com/
>
> smatch warnings:
> mm/vmalloc.c:3689 vread_iter() error: we previously assumed 'vm' could be null (see line 3667)
I see the code deficit, while the reproduce link seems to be unavilable.
Could you double check the link and provide a good one so that I can
verify the code fix?
Thanks
Baoquan
>
> vim +/vm +3689 mm/vmalloc.c
>
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3619 long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3620 {
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3621 struct vmap_area *va;
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3622 struct vm_struct *vm;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3623 char *vaddr;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3624 size_t n, size, flags, remains;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3625
> 4aff1dc4fb3a5a Andrey Konovalov 2022-03-24 3626 addr = kasan_reset_tag(addr);
> 4aff1dc4fb3a5a Andrey Konovalov 2022-03-24 3627
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3628 /* Don't allow overflow */
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3629 if ((unsigned long) addr + count < count)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3630 count = -(unsigned long) addr;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3631
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3632 remains = count;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3633
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3634 spin_lock(&vmap_area_lock);
> f181234a5a21fd Chen Wandun 2021-09-02 3635 va = find_vmap_area_exceed_addr((unsigned long)addr);
> f608788cd2d6ca Serapheim Dimitropoulos 2021-04-29 3636 if (!va)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3637 goto finished_zero;
> f181234a5a21fd Chen Wandun 2021-09-02 3638
> f181234a5a21fd Chen Wandun 2021-09-02 3639 /* no intersects with alive vmap_area */
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3640 if ((unsigned long)addr + remains <= va->va_start)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3641 goto finished_zero;
> f181234a5a21fd Chen Wandun 2021-09-02 3642
> f608788cd2d6ca Serapheim Dimitropoulos 2021-04-29 3643 list_for_each_entry_from(va, &vmap_area_list, list) {
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3644 size_t copied;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3645
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3646 if (remains == 0)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3647 goto finished;
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3648
> 06c8994626d1b7 Baoquan He 2023-02-06 3649 vm = va->vm;
> 06c8994626d1b7 Baoquan He 2023-02-06 3650 flags = va->flags & VMAP_FLAGS_MASK;
> 06c8994626d1b7 Baoquan He 2023-02-06 3651 /*
> 06c8994626d1b7 Baoquan He 2023-02-06 3652 * VMAP_BLOCK indicates a sub-type of vm_map_ram area, need
> 06c8994626d1b7 Baoquan He 2023-02-06 3653 * be set together with VMAP_RAM.
> 06c8994626d1b7 Baoquan He 2023-02-06 3654 */
> 06c8994626d1b7 Baoquan He 2023-02-06 3655 WARN_ON(flags == VMAP_BLOCK);
> 06c8994626d1b7 Baoquan He 2023-02-06 3656
> 06c8994626d1b7 Baoquan He 2023-02-06 3657 if (!vm && !flags)
>
> NULL check
>
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3658 continue;
> e81ce85f960c2e Joonsoo Kim 2013-04-29 3659
> 30a7a9b17c4b03 Baoquan He 2023-02-06 3660 if (vm && (vm->flags & VM_UNINITIALIZED))
> 30a7a9b17c4b03 Baoquan He 2023-02-06 3661 continue;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3662
> 30a7a9b17c4b03 Baoquan He 2023-02-06 3663 /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
> 30a7a9b17c4b03 Baoquan He 2023-02-06 3664 smp_rmb();
> 30a7a9b17c4b03 Baoquan He 2023-02-06 3665
> 06c8994626d1b7 Baoquan He 2023-02-06 3666 vaddr = (char *) va->va_start;
> 06c8994626d1b7 Baoquan He 2023-02-06 @3667 size = vm ? get_vm_area_size(vm) : va_size(va);
> 06c8994626d1b7 Baoquan He 2023-02-06 3668
> 06c8994626d1b7 Baoquan He 2023-02-06 3669 if (addr >= vaddr + size)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3670 continue;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3671
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3672 if (addr < vaddr) {
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3673 size_t to_zero = min_t(size_t, vaddr - addr, remains);
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3674 size_t zeroed = zero_iter(iter, to_zero);
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3675
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3676 addr += zeroed;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3677 remains -= zeroed;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3678
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3679 if (remains == 0 || zeroed != to_zero)
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3680 goto finished;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3681 }
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3682
> 06c8994626d1b7 Baoquan He 2023-02-06 3683 n = vaddr + size - addr;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3684 if (n > remains)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3685 n = remains;
> 06c8994626d1b7 Baoquan He 2023-02-06 3686
> 06c8994626d1b7 Baoquan He 2023-02-06 3687 if (flags & VMAP_RAM)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3688 copied = vmap_ram_vread_iter(iter, addr, n, flags);
> 06c8994626d1b7 Baoquan He 2023-02-06 @3689 else if (!(vm->flags & VM_IOREMAP))
> ^^^^^^^^^
> Unchecked dereference
>
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3690 copied = aligned_vread_iter(iter, addr, n);
> d0107eb07320b5 KAMEZAWA Hiroyuki 2009-09-21 3691 else /* IOREMAP area is treated as memory hole */
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3692 copied = zero_iter(iter, n);
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3693
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3694 addr += copied;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3695 remains -= copied;
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3696
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3697 if (copied != n)
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3698 goto finished;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3699 }
> d0107eb07320b5 KAMEZAWA Hiroyuki 2009-09-21 3700
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3701 finished_zero:
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3702 spin_unlock(&vmap_area_lock);
> d0107eb07320b5 KAMEZAWA Hiroyuki 2009-09-21 3703 /* zero-fill memory holes */
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3704 return count - remains + zero_iter(iter, remains);
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3705 finished:
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3706 /* Nothing remains, or We couldn't copy/zero everything. */
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3707 spin_unlock(&vmap_area_lock);
> d0107eb07320b5 KAMEZAWA Hiroyuki 2009-09-21 3708
> 4c91c07c93bbbd Lorenzo Stoakes 2023-03-22 3709 return count - remains;
> ^1da177e4c3f41 Linus Torvalds 2005-04-16 3710 }
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>
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