On Tue, Jan 02, 2024 at 08:03:46AM -0500, Michael S. Tsirkin wrote: > On Mon, Jan 01, 2024 at 05:38:24AM -0800, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: fbafc3e621c3 Merge tag 'for_linus' of git://git.kernel.org.. > > git tree: upstream > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=173df3e9e80000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=e0c7078a6b901aa3 > > dashboard link: https://syzkaller.appspot.com/bug?extid=d7521c1e3841ed075a42 > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1300b4a1e80000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=130b0379e80000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/1520f7b6daa4/disk-fbafc3e6.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/8b490af009d5/vmlinux-fbafc3e6.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/202ca200f4a4/bzImage-fbafc3e6.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+d7521c1e3841ed075a42@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ===================================================== Hi Alexander, Please take a look at this KMSAN failure. The uninitialized memory was created for the purpose of writing a coredump. vring_map_one_sg() should have direction=DMA_TO_DEVICE. I can't easily tell whether this is a genuine bug or an issue with commit 88938359e2df ("virtio: kmsan: check/unpoison scatterlist in vring_map_one_sg()"). Maybe coredump.c is writing out pages that KMSAN thinks are uninitialized? Stefan > > BUG: KMSAN: uninit-value in vring_map_one_sg drivers/virtio/virtio_ring.c:380 [inline] > > BUG: KMSAN: uninit-value in virtqueue_add_split drivers/virtio/virtio_ring.c:614 [inline] > > BUG: KMSAN: uninit-value in virtqueue_add+0x21c6/0x6530 drivers/virtio/virtio_ring.c:2210 > > vring_map_one_sg drivers/virtio/virtio_ring.c:380 [inline] > > virtqueue_add_split drivers/virtio/virtio_ring.c:614 [inline] > > virtqueue_add+0x21c6/0x6530 drivers/virtio/virtio_ring.c:2210 > > virtqueue_add_sgs+0x186/0x1a0 drivers/virtio/virtio_ring.c:2244 > > __virtscsi_add_cmd drivers/scsi/virtio_scsi.c:467 [inline] > > virtscsi_add_cmd+0x838/0xad0 drivers/scsi/virtio_scsi.c:501 > > virtscsi_queuecommand+0x896/0xa60 drivers/scsi/virtio_scsi.c:598 > > scsi_dispatch_cmd drivers/scsi/scsi_lib.c:1516 [inline] > > scsi_queue_rq+0x4874/0x5790 drivers/scsi/scsi_lib.c:1758 > > blk_mq_dispatch_rq_list+0x13f8/0x3600 block/blk-mq.c:2049 > > __blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline] > > blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline] > > __blk_mq_sched_dispatch_requests+0x10af/0x2500 block/blk-mq-sched.c:309 > > blk_mq_sched_dispatch_requests+0x160/0x2d0 block/blk-mq-sched.c:333 > > blk_mq_run_work_fn+0xd0/0x280 block/blk-mq.c:2434 > > process_one_work kernel/workqueue.c:2627 [inline] > > process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2700 > > worker_thread+0xf45/0x1490 kernel/workqueue.c:2781 > > kthread+0x3ed/0x540 kernel/kthread.c:388 > > ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147 > > ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 > > > > Uninit was created at: > > __alloc_pages+0x9a4/0xe00 mm/page_alloc.c:4591 > > alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133 > > alloc_pages mm/mempolicy.c:2204 [inline] > > folio_alloc+0x1da/0x380 mm/mempolicy.c:2211 > > filemap_alloc_folio+0xa5/0x430 mm/filemap.c:974 > > __filemap_get_folio+0xa5a/0x1760 mm/filemap.c:1918 > > ext4_da_write_begin+0x7f8/0xec0 fs/ext4/inode.c:2891 > > generic_perform_write+0x3f5/0xc40 mm/filemap.c:3918 > > ext4_buffered_write_iter+0x564/0xaa0 fs/ext4/file.c:299 > > ext4_file_write_iter+0x20f/0x3460 > > __kernel_write_iter+0x329/0x930 fs/read_write.c:517 > > dump_emit_page fs/coredump.c:888 [inline] > > dump_user_range+0x593/0xcd0 fs/coredump.c:915 > > elf_core_dump+0x528d/0x5a40 fs/binfmt_elf.c:2077 > > do_coredump+0x32c9/0x4920 fs/coredump.c:764 > > get_signal+0x2185/0x2d10 kernel/signal.c:2890 > > arch_do_signal_or_restart+0x53/0xca0 arch/x86/kernel/signal.c:309 > > exit_to_user_mode_loop+0xe8/0x320 kernel/entry/common.c:168 > > exit_to_user_mode_prepare+0x163/0x220 kernel/entry/common.c:204 > > irqentry_exit_to_user_mode+0xd/0x30 kernel/entry/common.c:309 > > irqentry_exit+0x16/0x40 kernel/entry/common.c:412 > > exc_page_fault+0x246/0x6f0 arch/x86/mm/fault.c:1564 > > asm_exc_page_fault+0x2b/0x30 arch/x86/include/asm/idtentry.h:570 > > > > Bytes 0-4095 of 4096 are uninitialized > > Memory access of size 4096 starts at ffff88812c79c000 > > > > CPU: 0 PID: 997 Comm: kworker/0:1H Not tainted 6.7.0-rc7-syzkaller-00003-gfbafc3e621c3 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 > > Workqueue: kblockd blk_mq_run_work_fn > > ===================================================== > > > > > > --- > > 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 syzbot to run the reproducer, reply with: > > #syz test: git://repo/address.git branch-or-commit-hash > > If you attach or paste a git patch, syzbot will apply it before testing. > > > > 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 >
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