Re: [PATCH] scsi: be2iscsi: Fix a theoretical leak in beiscsi_create_eqs()

Re: [PATCH] scsi: be2iscsi: Fix a theoretical leak in beiscsi_create_eqs()

[Thomas Lamprecht]

> The be_fill_queue() function can only fail when "eq_vaddress" is NULL
> and since it's non-NULL here that means the function call can't fail.
> But imagine if it could, then in that situation we would want to store
> the "paddr" so that dma memory can be released.
> 
> Fixes: bfead3b2cb46 ("[SCSI] be2iscsi: Adding msix and mcc_rings V3")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

This came in here through the stable 5.4 tree with v5.4.74, and we have some
users of ours report that it results in kernel oopses and delayed boot on their
HP DL 380 Gen 9 (and other Gen 9, FWICT) servers:

> systemd-udevd   D    0   501      1 0x80000000
> Call Trace:
>  __schedule+0x2e6/0x6f0
>  schedule+0x33/0xa0
>  schedule_timeout+0x205/0x330
>  wait_for_completion+0xb7/0x140
>  ? wake_up_q+0x80/0x80
>  __flush_work+0x131/0x1e0
>  ? worker_detach_from_pool+0xb0/0xb0
>  work_on_cpu+0x6d/0x90
>  ? workqueue_congested+0x80/0x80
>  ? pci_device_shutdown+0x60/0x60
>  pci_device_probe+0x190/0x1b0
>  really_probe+0x1c8/0x3e0
>  driver_probe_device+0xbb/0x100
>  device_driver_attach+0x58/0x60
>  __driver_attach+0x8f/0x150
>  ? device_driver_attach+0x60/0x60
>  bus_for_each_dev+0x79/0xc0
>  ? kmem_cache_alloc_trace+0x1a0/0x230
>  driver_attach+0x1e/0x20
>  bus_add_driver+0x154/0x1f0
>  ? 0xffffffffc0453000
>  driver_register+0x70/0xc0
>  ? 0xffffffffc0453000
>  __pci_register_driver+0x57/0x60
>  beiscsi_module_init+0x62/0x1000 [be2iscsi]
>  do_one_initcall+0x4a/0x1fa
>  ? _cond_resched+0x19/0x30
>  ? kmem_cache_alloc_trace+0x1a0/0x230
>  do_init_module+0x60/0x230
>  load_module+0x231b/0x2590
>  __do_sys_finit_module+0xbd/0x120
>  ? __do_sys_finit_module+0xbd/0x120
>  __x64_sys_finit_module+0x1a/0x20
>  do_syscall_64+0x57/0x190
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7f00aca06f59
> Code: Bad RIP value.
> RSP: 002b:00007ffc14380858 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
> RAX: ffffffffffffffda RBX: 0000558c726262e0 RCX: 00007f00aca06f59
> RDX: 0000000000000000 RSI: 00007f00ac90bcad RDI: 000000000000000e
> RBP: 00007f00ac90bcad R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000000e R11: 0000000000000246 R12: 0000000000000000
> R13: 0000558c725f6030 R14: 0000000000020000 R15: 0000558c726262e0

Blacklisting the be2iscsi module or reverting this commit helps, I did not get
around to look further into the mechanics at play and figured you would be
faster at that, or that this info at least helps someone else when searching
for the same symptoms.

cheers,
Thomas

Re: [PATCH] scsi: be2iscsi: Fix a theoretical leak in beiscsi_create_eqs()

[Dan Carpenter]

On Thu, Dec 03, 2020 at 11:10:09AM +0100, Thomas Lamprecht wrote:
> > The be_fill_queue() function can only fail when "eq_vaddress" is NULL
> > and since it's non-NULL here that means the function call can't fail.
> > But imagine if it could, then in that situation we would want to store
> > the "paddr" so that dma memory can be released.
> > 
> > Fixes: bfead3b2cb46 ("[SCSI] be2iscsi: Adding msix and mcc_rings V3")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> This came in here through the stable 5.4 tree with v5.4.74, and we have some
> users of ours report that it results in kernel oopses and delayed boot on their
> HP DL 380 Gen 9 (and other Gen 9, FWICT) servers:
> 

Thanks for the report Thomas.  I see the bug in my patch:

drivers/scsi/be2iscsi/be_main.c
  3008                  eq_for_mcc = 1;
  3009          else
  3010                  eq_for_mcc = 0;
  3011          for (i = 0; i < (phba->num_cpus + eq_for_mcc); i++) {
  3012                  eq = &phwi_context->be_eq[i].q;
  3013                  mem = &eq->dma_mem;
  3014                  phwi_context->be_eq[i].phba = phba;
  3015                  eq_vaddress = dma_alloc_coherent(&phba->pcidev->dev,
  3016                                                     num_eq_pages * PAGE_SIZE,
  3017                                                     &paddr, GFP_KERNEL);
  3018                  if (!eq_vaddress) {
  3019                          ret = -ENOMEM;
  3020                          goto create_eq_error;
  3021                  }
  3022  
  3023                  mem->dma = paddr;
                        ^^^^^^^^^^^^^^^^
I moved this assignment ahead of the call to be_fill_queue().

  3024                  mem->va = eq_vaddress;
  3025                  ret = be_fill_queue(eq, phba->params.num_eq_entries,
  3026                                      sizeof(struct be_eq_entry), eq_vaddress);
  3027                  if (ret) {
  3028                          beiscsi_log(phba, KERN_ERR, BEISCSI_LOG_INIT,
  3029                                      "BM_%d : be_fill_queue Failed for EQ\n");
  3030                          goto create_eq_error;
  3031                  }


drivers/scsi/be2iscsi/be_main.c
  2978  static int be_fill_queue(struct be_queue_info *q,
  2979                  u16 len, u16 entry_size, void *vaddress)
  2980  {
  2981          struct be_dma_mem *mem = &q->dma_mem;
  2982  
  2983          memset(q, 0, sizeof(*q));
                ^^^^^^^^^^^^^^^^^^^^^^^
But the first thing that it does is it overwrites it with zeros.

  2984          q->len = len;
  2985          q->entry_size = entry_size;
  2986          mem->size = len * entry_size;
  2987          mem->va = vaddress;

It also overwrites the "mem->va = eq_vaddress;" assignment as well, but
but it sets that back again here...

  2988          if (!mem->va)
  2989                  return -ENOMEM;
  2990          memset(mem->va, 0, mem->size);
  2991          return 0;
  2992  }

I will just revert my patch.  This code is messy but it works so far as
I can see.

regards,
dan carpenter

[PATCH] scsi: be2iscsi: revert "Fix a theoretical leak in beiscsi_create_eqs()"

[Dan Carpenter]

My patch caused kernel Oopses and delays in boot.  Revert it.

The problem was that I moved the "mem->dma = paddr;" before the call to
be_fill_queue().  But the first thing that the be_fill_queue() function
does is memset the whole struct to zero which overwrites the assignment.

Fixes: 38b2db564d9a ("scsi: be2iscsi: Fix a theoretical leak in beiscsi_create_eqs()")
Reported-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
My original patch was basically a clean up patch and to try silence a
static checker warning.  I've already updated the static checker to not
warn about impossible leaks and in this case we know that be_fill_queue()
cannot fail.

I was tempted to delete the "mem->va = eq_vaddress;" assignment as a
clean up but I didn't.  :P

 drivers/scsi/be2iscsi/be_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index 50e464224d47..90fcddb76f46 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -3020,7 +3020,6 @@ static int beiscsi_create_eqs(struct beiscsi_hba *phba,
 			goto create_eq_error;
 		}
 
-		mem->dma = paddr;
 		mem->va = eq_vaddress;
 		ret = be_fill_queue(eq, phba->params.num_eq_entries,
 				    sizeof(struct be_eq_entry), eq_vaddress);
@@ -3030,6 +3029,7 @@ static int beiscsi_create_eqs(struct beiscsi_hba *phba,
 			goto create_eq_error;
 		}
 
+		mem->dma = paddr;
 		ret = beiscsi_cmd_eq_create(&phba->ctrl, eq,
 					    BEISCSI_EQ_DELAY_DEF);
 		if (ret) {
@@ -3086,7 +3086,6 @@ static int beiscsi_create_cqs(struct beiscsi_hba *phba,
 			goto create_cq_error;
 		}
 
-		mem->dma = paddr;
 		ret = be_fill_queue(cq, phba->params.num_cq_entries,
 				    sizeof(struct sol_cqe), cq_vaddress);
 		if (ret) {
@@ -3096,6 +3095,7 @@ static int beiscsi_create_cqs(struct beiscsi_hba *phba,
 			goto create_cq_error;
 		}
 
+		mem->dma = paddr;
 		ret = beiscsi_cmd_cq_create(&phba->ctrl, cq, eq, false,
 					    false, 0);
 		if (ret) {
-- 
2.29.2

Re: [PATCH] scsi: be2iscsi: revert "Fix a theoretical leak in beiscsi_create_eqs()"

[Greg KH]

On Thu, Dec 03, 2020 at 03:18:26PM +0300, Dan Carpenter wrote:
> My patch caused kernel Oopses and delays in boot.  Revert it.
> 
> The problem was that I moved the "mem->dma = paddr;" before the call to
> be_fill_queue().  But the first thing that the be_fill_queue() function
> does is memset the whole struct to zero which overwrites the assignment.
> 
> Fixes: 38b2db564d9a ("scsi: be2iscsi: Fix a theoretical leak in beiscsi_create_eqs()")
> Reported-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Can someone please add:
	Cc: stable <stable@vger.kernel.org>
to this so we know to pick it up quickly there?

thanks,

greg k-h

Re: [PATCH] scsi: be2iscsi: revert "Fix a theoretical leak in beiscsi_create_eqs()"

[Martin K. Petersen]

On Thu, 3 Dec 2020 15:18:26 +0300, Dan Carpenter wrote:

> My patch caused kernel Oopses and delays in boot.  Revert it.
> 
> The problem was that I moved the "mem->dma = paddr;" before the call to
> be_fill_queue().  But the first thing that the be_fill_queue() function
> does is memset the whole struct to zero which overwrites the assignment.

Added Cc: stable and applied to 5.10/scsi-fixes, thanks!

[1/1] scsi: be2iscsi: revert "Fix a theoretical leak in beiscsi_create_eqs()"
      https://git.kernel.org/mkp/scsi/c/eeaf06af6f87

-- 
Martin K. Petersen	Oracle Linux Engineering