90b0296ece
Syzbot found the following issue: general protection fault, probably for non-canonical address 0xdffffc000000001d: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef] CPU: 0 PID: 5234 Comm: syz-executor931 Not tainted 6.1.0-rc3-next-20221102-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022 RIP: 0010:__elevator_get block/elevator.h:94 [inline] RIP: 0010:blk_mq_elv_switch_none block/blk-mq.c:4593 [inline] RIP: 0010:__blk_mq_update_nr_hw_queues block/blk-mq.c:4658 [inline] RIP: 0010:blk_mq_update_nr_hw_queues+0x304/0xe40 block/blk-mq.c:4709 RSP: 0018:ffffc90003cdfc08 EFLAGS: 00010206 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 000000000000001d RSI: 0000000000000002 RDI: 00000000000000e8 RBP: ffff88801dbd0000 R08: ffff888027c89398 R09: ffffffff8de2e517 R10: fffffbfff1bc5ca2 R11: 0000000000000000 R12: ffffc90003cdfc70 R13: ffff88801dbd0008 R14: ffff88801dbd03f8 R15: ffff888027c89380 FS: 0000555557259300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000005d84c8 CR3: 000000007a7cb000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> nbd_start_device+0x153/0xc30 drivers/block/nbd.c:1355 nbd_start_device_ioctl drivers/block/nbd.c:1405 [inline] __nbd_ioctl drivers/block/nbd.c:1481 [inline] nbd_ioctl+0x5a1/0xbd0 drivers/block/nbd.c:1521 blkdev_ioctl+0x36e/0x800 block/ioctl.c:614 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd As after dd6f7f17bf58 commit move '__elevator_get(qe->type)' before set 'qe->type', so will lead to access wild pointer. To solve above issue get 'qe->type' after set 'qe->type'. Reported-by: syzbot+746a4eece09f86bc39d7@syzkaller.appspotmail.com Fixes:dd6f7f17bf58("block: add proper helpers for elevator_type module refcount management") Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221107033956.3276891-1-yebin@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.