mm/vmalloc.c:3689 vread_iter() error: we previously assumed 'vm' could be null (see line 3667)
From: Dan Carpenter
Date: Tue Oct 17 2023 - 10:26:49 EST
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@xxxxxxxxx/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231017/202310171600.WCrsOwFj-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
| Closes: https://lore.kernel.org/r/202310171600.WCrsOwFj-lkp@xxxxxxxxx/
smatch warnings:
mm/vmalloc.c:3689 vread_iter() error: we previously assumed 'vm' could be null (see line 3667)
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 }
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