Re: [bug report] NULL pointer at blk_mq_put_rq_ref+0x20/0xb4 observed with blktests on 5.13.15

[Ming Lei <ming.lei@redhat.com>]

On Thu, Sep 09, 2021 at 12:07:32PM +0200, Greg KH wrote:
> On Thu, Sep 09, 2021 at 05:14:18PM +0800, Ming Lei wrote:
> > On Thu, Sep 9, 2021 at 4:47 PM Yi Zhang <yi.zhang@redhat.com> wrote:
> > >
> > > Hello
> > >
> > > I found this issue with blktests on[1], did we miss some patch on stable?
> > > [1]
> > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
> > > queue/5.13
> > >
> > > [   68.989907] run blktests block/006 at 2021-09-09 04:34:35
> > > [   69.085724] null_blk: module loaded
> > > [   74.271624] Unable to handle kernel NULL pointer dereference at
> > > virtual address 00000000000002b8
> > > [   74.280414] Mem abort info:
> > > [   74.283195]   ESR = 0x96000004
> > > [   74.286245]   EC = 0x25: DABT (current EL), IL = 32 bits
> > > [   74.291545]   SET = 0, FnV = 0
> > > [   74.294587]   EA = 0, S1PTW = 0
> > > [   74.297720] Data abort info:
> > > [   74.300588]   ISV = 0, ISS = 0x00000004
> > > [   74.304411]   CM = 0, WnR = 0
> > > [   74.307368] user pgtable: 4k pages, 48-bit VAs, pgdp=000008004366e000
> > > [   74.313796] [00000000000002b8] pgd=0000000000000000, p4d=0000000000000000
> > > [   74.320577] Internal error: Oops: 96000004 [#1] SMP
> > > [   74.325443] Modules linked in: null_blk mlx5_ib ib_uverbs ib_core
> > > rfkill sunrpc vfat fat joydev acpi_ipmi ipmi_ssif cdc_ether usbnet mii
> > > mlx5_core psample ipmi_devintf mlxfw tls ipmi_msghandler arm_cmn
> > > cppc_cpufreq arm_dsu_pmu acpi_tad fuse zram ip_tables xfs ast
> > > i2c_algo_bit drm_vram_helper drm_kms_helper crct10dif_ce syscopyarea
> > > ghash_ce sysfillrect uas sysimgblt sbsa_gwdt fb_sys_fops cec
> > > drm_ttm_helper ttm nvme usb_storage nvme_core drm xgene_hwmon
> > > aes_neon_bs
> > > [   74.366458] CPU: 31 PID: 2511 Comm: fio Not tainted 5.13.15+ #1
> > 
> > Looks the fixes haven't land on linux-5.13.y:
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a9ed27a764156929efe714033edb3e9023c5f321
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2da19ed50554ce52ecbad3655c98371fe58599f
> 
> Now queued up.  Someone could have told us they were needed :)

Thanks for queuing it up, sorry for not Cc stable.

BTW, the following two patches are missed too in linux-5.13-y:

364b61818f65 blk-mq: clearing flush request reference in tags->rqs[]
bd63141d585b blk-mq: clear stale request in tags->rq[] before freeing one request pool

Both can fix request UAF issue.

Thanks, 
Ming