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AJvYcCWO881e/lPrZ55qSYg+JICU2ZHG983ixwaPXLYtW6zVJYEtO457DBWvbfxtEJ1OPkeB9IUriHcPAvcZri7R@vger.kernel.org X-Gm-Message-State: AOJu0YyDhv1mp1CFuh355IkS0IVczHt7tYmeZnJnMChTs3PteztZo6nP TLGhk2GwxyvmwJj1iMoIElbTjQlqtxTgsLBPAPuLsUICBpw4LSXfihDIAyYZ4sXdYq7Lh7VcseZ yiiNfLPEd0id3b12KkakZhfJ5lkfD9RgOKitw17po63vd8rpG5kHk7Qc7xTk= Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:81cb:b0:679:f11b:a511 with SMTP id 006d021491bc7-67b9bd1690dmr825645eaf.45.1772778978939; Thu, 05 Mar 2026 22:36:18 -0800 (PST) Date: Thu, 05 Mar 2026 22:36:18 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69aa75e2.050a0220.13f275.0010.GAE@google.com> Subject: [syzbot] [netfs?] BUG: unable to handle kernel NULL pointer dereference in netfs_unbuffered_write From: syzbot To: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netfs@lists.linux.dev, pc@manguebit.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: c107785c7e8d Merge tag 'modules-7.0-rc3.fixes' of git://gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15db7b5a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=976ba5a93c4add9e dashboard link: https://syzkaller.appspot.com/bug?extid=7227db0fbac9f348dba0 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1628ab5a580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16a5414a580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-c107785c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3a4a4abcd973/vmlinux-c107785c.xz kernel image: https://storage.googleapis.com/syzbot-assets/f60667f16840/bzImage-c107785c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7227db0fbac9f348dba0@syzkaller.appspotmail.com netfs: Couldn't get user pages (rc=-14) BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 31867067 P4D 31867067 PUD 0 Oops: Oops: 0010 [#1] SMP KASAN NOPTI CPU: 3 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffc90003b7fb90 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88803bd3a5b0 RCX: ffffffff82c49d0a RDX: ffff88802b9ca4c0 RSI: ffffffff82c49b9c RDI: ffff88803bd3a500 RBP: 0000000000140000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88803bd3a598 R13: dffffc0000000000 R14: ffff88803bd3a500 R15: ffff888023066580 FS: 00007f9e9a09f6c0(0000) GS:ffff8880d6644000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 000000002c65b000 CR4: 0000000000352ef0 Call Trace: netfs_unbuffered_write+0xae5/0x2080 fs/netfs/direct_write.c:189 netfs_unbuffered_write_iter_locked+0x801/0xab0 fs/netfs/direct_write.c:287 netfs_unbuffered_write_iter+0x40c/0x710 fs/netfs/direct_write.c:377 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9e9919c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9e9a09f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f9e99415fa0 RCX: 00007f9e9919c799 RDX: 000000000208e24b RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007f9e99232bd9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9e99416038 R14: 00007f9e99415fa0 R15: 00007fff05034208 Modules linked in: CR2: 0000000000000000 ---[ end trace 0000000000000000 ]--- RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffc90003b7fb90 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88803bd3a5b0 RCX: ffffffff82c49d0a RDX: ffff88802b9ca4c0 RSI: ffffffff82c49b9c RDI: ffff88803bd3a500 RBP: 0000000000140000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88803bd3a598 R13: dffffc0000000000 R14: ffff88803bd3a500 R15: ffff888023066580 FS: 00007f9e9a09f6c0(0000) GS:ffff8880d6644000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 000000002c65b000 CR4: 0000000000352ef0 --- 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@googlegroups.com. 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