On Mon, Apr 29, 2024 at 11:02 PM syzbot <syzbot+9c9d60f1b20b22ce218a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: e33c4963bf53 Merge tag 'nfsd-6.9-5' of git://git.kernel.or.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=123d5a0f180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=776c05250f36d55c > dashboard link: https://syzkaller.appspot.com/bug?extid=9c9d60f1b20b22ce218a > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/a10175188ebb/disk-e33c4963.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/abe743417d16/vmlinux-e33c4963.xz > kernel image: https://storage.googleapis.com/syzbot-assets/fb10cccc9909/bzImage-e33c4963.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+9c9d60f1b20b22ce218a@xxxxxxxxxxxxxxxxxxxxxxxxx > > ===================================================== > BUG: KMSAN: uninit-value in zswap_rb_insert+0x1e9/0x330 mm/zswap.c:842 I am not sure how this could happen. The report is complaining about the access in the loop condition AFAICT: while (*link) { /* here */ .. } *link should start as root->rb_node (which should be NULL as it is static data), then be updated to point at a zswap_entry->rbnode as entries get added. *link should keep then be updated to values at zswap_entry->rbnode->{left/right}. Although entry->rbnode->{left/right} are not initialized when allocated by zswap_entry_cache_alloc() as the report mentions, they are initialized in zswap_rb_insert()->rb_link_node() when they are added to the tree. Also, this code is removed with the xarray conversion anyway. > zswap_rb_insert+0x1e9/0x330 mm/zswap.c:842 > zswap_store+0x22f2/0x2ca0 mm/zswap.c:1591 > swap_writepage+0x126/0x4c0 mm/page_io.c:198 > pageout mm/vmscan.c:660 [inline] > shrink_folio_list+0x4a55/0x7910 mm/vmscan.c:1323 > evict_folios+0x9d7f/0xcc20 mm/vmscan.c:4537 > try_to_shrink_lruvec+0x160e/0x1a50 mm/vmscan.c:4733 > shrink_one+0x66f/0xd40 mm/vmscan.c:4772 > shrink_many mm/vmscan.c:4835 [inline] > lru_gen_shrink_node mm/vmscan.c:4935 [inline] > shrink_node+0x4856/0x55f0 mm/vmscan.c:5894 > shrink_zones mm/vmscan.c:6152 [inline] > do_try_to_free_pages+0x820/0x2570 mm/vmscan.c:6214 > try_to_free_pages+0xb7b/0x1820 mm/vmscan.c:6449 > __perform_reclaim mm/page_alloc.c:3774 [inline] > __alloc_pages_direct_reclaim mm/page_alloc.c:3796 [inline] > __alloc_pages_slowpath+0x1035/0x31a0 mm/page_alloc.c:4202 > __alloc_pages+0xacf/0xe70 mm/page_alloc.c:4588 > alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264 > vma_alloc_folio+0x418/0x680 mm/mempolicy.c:2303 > do_cow_fault mm/memory.c:4918 [inline] > do_fault mm/memory.c:5026 [inline] > do_pte_missing mm/memory.c:3880 [inline] > handle_pte_fault mm/memory.c:5300 [inline] > __handle_mm_fault mm/memory.c:5441 [inline] > handle_mm_fault+0x4f2f/0xce00 mm/memory.c:5606 > do_user_addr_fault arch/x86/mm/fault.c:1413 [inline] > handle_page_fault arch/x86/mm/fault.c:1505 [inline] > exc_page_fault+0x2a0/0x730 arch/x86/mm/fault.c:1563 > asm_exc_page_fault+0x2b/0x30 arch/x86/include/asm/idtentry.h:623 > rep_stos_alternative+0x40/0x80 arch/x86/lib/clear_page_64.S:92 > load_elf_binary+0x212e/0x4d30 fs/binfmt_elf.c:1132 > search_binary_handler fs/exec.c:1778 [inline] > exec_binprm fs/exec.c:1820 [inline] > bprm_execve+0xc57/0x21c0 fs/exec.c:1872 > do_execveat_common+0xceb/0xd70 fs/exec.c:1979 > do_execve fs/exec.c:2053 [inline] > __do_sys_execve fs/exec.c:2129 [inline] > __se_sys_execve fs/exec.c:2124 [inline] > __x64_sys_execve+0xf4/0x130 fs/exec.c:2124 > x64_sys_call+0x1612/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:60 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Uninit was created at: > __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598 > __alloc_pages_node include/linux/gfp.h:238 [inline] > alloc_pages_node include/linux/gfp.h:261 [inline] > alloc_slab_page mm/slub.c:2175 [inline] > allocate_slab mm/slub.c:2338 [inline] > new_slab+0x2de/0x1400 mm/slub.c:2391 > ___slab_alloc+0x1184/0x33d0 mm/slub.c:3525 > __slab_alloc mm/slub.c:3610 [inline] > __slab_alloc_node mm/slub.c:3663 [inline] > slab_alloc_node mm/slub.c:3835 [inline] > kmem_cache_alloc_node+0x6ea/0xc50 mm/slub.c:3888 > zswap_entry_cache_alloc mm/zswap.c:874 [inline] > zswap_store+0xb26/0x2ca0 mm/zswap.c:1535 > swap_writepage+0x126/0x4c0 mm/page_io.c:198 > pageout mm/vmscan.c:660 [inline] > shrink_folio_list+0x4a55/0x7910 mm/vmscan.c:1323 > evict_folios+0x9d7f/0xcc20 mm/vmscan.c:4537 > try_to_shrink_lruvec+0x160e/0x1a50 mm/vmscan.c:4733 > shrink_one+0x66f/0xd40 mm/vmscan.c:4772 > shrink_many mm/vmscan.c:4835 [inline] > lru_gen_shrink_node mm/vmscan.c:4935 [inline] > shrink_node+0x4856/0x55f0 mm/vmscan.c:5894 > shrink_zones mm/vmscan.c:6152 [inline] > do_try_to_free_pages+0x820/0x2570 mm/vmscan.c:6214 > try_to_free_pages+0xb7b/0x1820 mm/vmscan.c:6449 > __perform_reclaim mm/page_alloc.c:3774 [inline] > __alloc_pages_direct_reclaim mm/page_alloc.c:3796 [inline] > __alloc_pages_slowpath+0x1035/0x31a0 mm/page_alloc.c:4202 > __alloc_pages+0xacf/0xe70 mm/page_alloc.c:4588 > alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264 > alloc_pages+0x1bf/0x1e0 mm/mempolicy.c:2335 > vm_area_alloc_pages mm/vmalloc.c:3561 [inline] > __vmalloc_area_node mm/vmalloc.c:3637 [inline] > __vmalloc_node_range+0x100a/0x28b0 mm/vmalloc.c:3818 > vmalloc_user+0x90/0xb0 mm/vmalloc.c:3972 > kcov_ioctl+0x5d/0x660 kernel/kcov.c:704 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:904 [inline] > __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890 > __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890 > x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > CPU: 0 PID: 5281 Comm: dhcpcd-run-hook Not tainted 6.9.0-rc5-syzkaller-00053-ge33c4963bf53 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 > ===================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup
