Re: [PATCH for-next] RDMA/bnxt_re: Fix kernel panic when trying to access bnxt_re_stat_descs

[Leon Romanovsky <leon@kernel.org>]

On Wed, Oct 27, 2021 at 11:54:48PM +0300, Kamal Heib wrote:
> For some reason when introducing 13f30b0fa0a9 commit the "active_pds" and
> "active_ahs" descriptors got dropped, which lead to the following panic
> when trying to access the first entry in the descriptors. Avoid this by
> return the dropped hunks.
> 
>  bnxt_re: Broadcom NetXtreme-C/E RoCE Driver
>  BUG: kernel NULL pointer dereference, address: 0000000000000000
>  #PF: supervisor read access in kernel mode
>  #PF: error_code(0x0000) - not-present page
>  PGD 0 P4D 0
>  Oops: 0000 [#1] SMP PTI
>  CPU: 2 PID: 594 Comm: kworker/u32:1 Not tainted 5.15.0-rc6+ #2
>  Hardware name: Dell Inc. PowerEdge R430/0CN7X8, BIOS 2.12.1 12/07/2020
>  Workqueue: bnxt_re bnxt_re_task [bnxt_re]
>  RIP: 0010:strlen+0x0/0x20
>  Code: 48 89 f9 74 09 48 83 c1 01 80 39 00 75 f7 31 d2 44 0f b6 04 16 44 88 04 11 48 83 c2 01 45 84 c0 75 ee c3 0f 1f 80 00 00 00 00 <80> 3f 00 74 10 48 89 f8 48 83 c0 01 80 31
>  RSP: 0018:ffffb25fc47dfbb0 EFLAGS: 00010246
>  RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000008100
>  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>  RBP: 0000000000000000 R08: 00000000fffffff4 R09: 0000000000000000
>  R10: ffff8a05c71fc028 R11: 0000000000000000 R12: 0000000000000000
>  R13: 0000000000000000 R14: 0000000000000000 R15: ffff8a05c3dee800
>  FS:  0000000000000000(0000) GS:ffff8a092fc40000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000000000000 CR3: 000000048d3da001 CR4: 00000000001706e0
>  Call Trace:
>   kernfs_name_hash+0x12/0x80
>   kernfs_find_ns+0x35/0xd0
>   kernfs_remove_by_name_ns+0x32/0x90
>   remove_files+0x2b/0x60
>   create_files+0x1d3/0x1f0
>   internal_create_group+0x17b/0x1f0
>   internal_create_groups.part.0+0x3d/0xa0
>   setup_port+0x180/0x3b0 [ib_core]
>   ? __cond_resched+0x16/0x40
>   ? kmem_cache_alloc_trace+0x278/0x3d0
>   ib_setup_port_attrs+0x99/0x240 [ib_core]
>   ib_register_device+0xcc/0x160 [ib_core]
>   bnxt_re_task+0xba/0x170 [bnxt_re]
>   process_one_work+0x1eb/0x390
>   worker_thread+0x53/0x3d0
>   ? process_one_work+0x390/0x390
>   kthread+0x10f/0x130
>   ? set_kthread_struct+0x40/0x40
>   ret_from_fork+0x22/0x30
>  Modules linked in: bnxt_re kvm ib_uverbs dell_wmi_descriptor rfkill video iTCO_wdt iTCO_vendor_support irqbypass dcdbas ib_core ipmi_ssif rapl intel_cstate intel_uncore pcspke
>  CR2: 0000000000000000
>  ---[ end trace b4637e4c4e3001af ]---
>  RIP: 0010:strlen+0x0/0x20
>  Code: 48 89 f9 74 09 48 83 c1 01 80 39 00 75 f7 31 d2 44 0f b6 04 16 44 88 04 11 48 83 c2 01 45 84 c0 75 ee c3 0f 1f 80 00 00 00 00 <80> 3f 00 74 10 48 89 f8 48 83 c0 01 80 31
>  RSP: 0018:ffffb25fc47dfbb0 EFLAGS: 00010246
>  RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000008100
>  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>  RBP: 0000000000000000 R08: 00000000fffffff4 R09: 0000000000000000
>  R10: ffff8a05c71fc028 R11: 0000000000000000 R12: 0000000000000000
>  R13: 0000000000000000 R14: 0000000000000000 R15: ffff8a05c3dee800
>  FS:  0000000000000000(0000) GS:ffff8a092fc40000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 0000000000000000 CR3: 000000048d3da001 CR4: 00000000001706e0
>  Kernel panic - not syncing: Fatal exception
>  Kernel Offset: 0x400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
>  ---[ end Kernel panic - not syncing: Fatal exception ]---
> 
> Fixes: 13f30b0fa0a9 ("RDMA/counter: Add a descriptor in struct rdma_hw_stats")
> Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
> ---
>  drivers/infiniband/hw/bnxt_re/hw_counters.c | 2 ++
>  1 file changed, 2 insertions(+)
> 

Sorry about that.

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>