New: Function beiscsi_create_cqs() may return improper value when the call to pci_alloc_consistent() fails, which may result in use-after-free

https://bugzilla.kernel.org/show_bug.cgi?id=188941

Bug ID: 188941
Summary: Function beiscsi_create_cqs() may return improper
value when the call to pci_alloc_consistent() fails, which may result in use-after-free
Product: SCSI Drivers
Version: 2.5
Kernel Version: linux-4.9-rc6
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Other
Assignee: [email protected]
Reporter: [email protected]
Regression: No

Function pci_alloc_consistent() returns a NULL pointer if there is no enough memory. In function beiscsi_create_cqs() defined in file drivers/scsi/be2iscsi/be_main.c, function pci_alloc_consistent() is called and its return value is checked against NULL (at line 3116). If the return value is NULL, the control flow will jump to label "create_cq_error", frees allocated memory and returns variable ret. Because after the first execution of the loop the value of ret must be 0 (see the check statement of ret at line 3129), the return value will be 0 (indicates success) if pci_alloc_consistent() fails during the second or after repeats of the loop body. In this case, the freed memory may be used or freed again in the callers of beiscsi_create_cqs(). I think it is better to assign "-ENOMEM" when the call pci_alloc_consistent() fails. Codes and comments related to this bug are summarised as follows.

beiscsi_create_cqs @@ drivers/scsi/be2iscsi/be_main.c 3092 static int beiscsi_create_cqs(struct beiscsi_hba *phba,
3093 struct hwi_context_memory *phwi_context)

3094 {
         ...
3100     int ret = -ENOMEM;
         ...
3106     for (i = 0; i < phba->num_cpus; i++) {
3107         cq = &phwi_context->be_cq[i];
3108         eq = &phwi_context->be_eq[i].q;
3109         pbe_eq = &phwi_context->be_eq[i];
3110         pbe_eq->cq = cq;
3111         pbe_eq->phba = phba;
3112         mem = &cq->dma_mem;
3113         cq_vaddress = pci_alloc_consistent(phba->pcidev,
3114                            num_cq_pages * PAGE_SIZE,
3115                            &paddr);
3116         if (!cq_vaddress)
                 // ret may takes value 0. Add "ret = -ENOMEM" here?
3117             goto create_cq_error;
             ...

3129 ret = beiscsi_cmd_cq_create(&phba->ctrl, cq, eq, false,
3130 false, 0);
3131 if (ret) {
3132 beiscsi_log(phba, KERN_ERR, BEISCSI_LOG_INIT,
3133 "BM_%d : beiscsi_cmd_eq_create"
3134 "Failed for ISCSI CQ\n");
3135 goto create_cq_error;
3136 }
3137 beiscsi_log(phba, KERN_INFO, BEISCSI_LOG_INIT,
3138 "BM_%d : iscsi cq_id is %d for eq_id %d\n"
3139 "iSCSI CQ CREATED\n", cq->id, eq->id);
3140 }
3141 return 0;
3142
3143 create_cq_error:
3144 for (i = 0; i < phba->num_cpus; i++) {

3145         cq = &phwi_context->be_cq[i];
3146         mem = &cq->dma_mem;
3147         if (mem->va)

3148 pci_free_consistent(phba->pcidev, num_cq_pages
3149 * PAGE_SIZE,
3150 mem->va, mem->dma);
3151 }
3152 return ret;
3153 }

Thanks very much!

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https://bugzilla.kernel.org/show_bug.cgi?id=188941

--- Comment #1 from bianpan ([email protected]) --- Created attachment 256439
--> https://bugzilla.kernel.org/attachment.cgi?id=256439&action=edit
The patch fixes the bug

The patch has been merged into the latest version of the Linux kernel. So I will close the bug.

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https://bugzilla.kernel.org/show_bug.cgi?id=188941

bianpan ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |RESOLVED
         Resolution|---                         |CODE_FIX

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