On Mon, 24 Apr 2023 at 09:21, syzbot <syzbot+ec4650f158c91a963120@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: cb0856346a60 Merge tag 'mm-hotfixes-stable-2023-04-19-16-3.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=170802cfc80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=fa4baf7c6b35b5d5 > dashboard link: https://syzkaller.appspot.com/bug?extid=ec4650f158c91a963120 > compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/a02dd7789fb2/disk-cb085634.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/a1a1eac454f6/vmlinux-cb085634.xz > kernel image: https://storage.googleapis.com/syzbot-assets/bb0447014913/bzImage-cb085634.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+ec4650f158c91a963120@xxxxxxxxxxxxxxxxxxxxxxxxx shmem_recalc_inode() has a check for "freed > 0", but I think it can be violated due to this race, if i_mapping->nrpages is read twice. If there are concurrent modifications, the code should use at least READ/WRITE_ONCE for accesses. > ================================================================== > BUG: KCSAN: data-race in __filemap_remove_folio / shmem_get_folio_gfp > > read-write to 0xffff888136bf8960 of 8 bytes by task 19402 on cpu 1: > page_cache_delete mm/filemap.c:147 [inline] > __filemap_remove_folio+0x22f/0x330 mm/filemap.c:225 > filemap_remove_folio+0x6c/0x220 mm/filemap.c:257 > truncate_inode_folio+0x19f/0x1e0 mm/truncate.c:196 > shmem_undo_range+0x24d/0xc20 mm/shmem.c:942 > shmem_truncate_range mm/shmem.c:1041 [inline] > shmem_fallocate+0x2fc/0x8d0 mm/shmem.c:2779 > vfs_fallocate+0x369/0x3d0 fs/open.c:324 > madvise_remove mm/madvise.c:1001 [inline] > madvise_vma_behavior mm/madvise.c:1025 [inline] > madvise_walk_vmas mm/madvise.c:1260 [inline] > do_madvise+0x77b/0x28a0 mm/madvise.c:1439 > __do_sys_madvise mm/madvise.c:1452 [inline] > __se_sys_madvise mm/madvise.c:1450 [inline] > __x64_sys_madvise+0x60/0x70 mm/madvise.c:1450 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > read to 0xffff888136bf8960 of 8 bytes by task 19400 on cpu 0: > shmem_recalc_inode mm/shmem.c:359 [inline] > shmem_get_folio_gfp+0xc0a/0x1120 mm/shmem.c:1977 > shmem_fault+0xd9/0x3d0 mm/shmem.c:2152 > __do_fault mm/memory.c:4155 [inline] > do_read_fault mm/memory.c:4506 [inline] > do_fault mm/memory.c:4635 [inline] > handle_pte_fault mm/memory.c:4923 [inline] > __handle_mm_fault mm/memory.c:5065 [inline] > handle_mm_fault+0x115d/0x21d0 mm/memory.c:5211 > faultin_page mm/gup.c:925 [inline] > __get_user_pages+0x363/0xc30 mm/gup.c:1147 > populate_vma_page_range mm/gup.c:1543 [inline] > __mm_populate+0x23a/0x360 mm/gup.c:1652 > mm_populate include/linux/mm.h:3026 [inline] > vm_mmap_pgoff+0x174/0x210 mm/util.c:547 > ksys_mmap_pgoff+0xc5/0x320 mm/mmap.c:1410 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > value changed: 0x0000000000000437 -> 0x0000000000000430 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 0 PID: 19400 Comm: syz-executor.3 Not tainted 6.3.0-rc7-syzkaller-00089-gcb0856346a60 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 > ================================================================== > > > --- > 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. > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000fb55ed05fa0fdb4b%40google.com.
