| Message ID | 20221028050736.151185-1-zyytlz.wz@163.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | scsi: lpfc: fix double free bug in lpfc_bsg_write_ebuf_set | expand |
Friendly ping :)
On 10/27/2022 10:07 PM, Zheng Wang wrote: > When error occurs, it frees dmabuf in both lpfc_bsg_write_ebuf_set > and lpfc_bsg_issue_mbox. > > Fix it by removing free code in lpfc_bsg_write_ebuf_set. > > Reported-by: Zheng Wang <hackerzheng666@gmail.com> > Reported-by: Zhuorao Yang <alex000young@gmail.com> > > Fixes: 7ad20aa9d39a ("[SCSI] lpfc 8.3.24: Extend BSG infrastructure and add link diagnostics") > > Signed-off-by: Zheng Wang <zyytlz.wz@163.com> > --- > drivers/scsi/lpfc/lpfc_bsg.c | 17 +++-------------- > 1 file changed, 3 insertions(+), 14 deletions(-) > > diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c > index ac0c7ccf2eae..7362d9c1a50b 100644 > --- a/drivers/scsi/lpfc/lpfc_bsg.c > +++ b/drivers/scsi/lpfc/lpfc_bsg.c > @@ -4439,15 +4439,13 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, > > dd_data = kmalloc(sizeof(struct bsg_job_data), GFP_KERNEL); > if (!dd_data) { > - rc = -ENOMEM; > - goto job_error; > + return -ENOMEM; > } > > /* mailbox command structure for base driver */ > pmboxq = mempool_alloc(phba->mbox_mem_pool, GFP_KERNEL); > if (!pmboxq) { > - rc = -ENOMEM; > - goto job_error; > + return -ENOMEM; > } > memset(pmboxq, 0, sizeof(LPFC_MBOXQ_t)); > pbuf = (uint8_t *)phba->mbox_ext_buf_ctx.mbx_dmabuf->virt; Minimally, just looking at this one snippet, by returning after the mempool_alloc() failure, we are leaking the dd_data memory just allocated. > @@ -4480,8 +4478,7 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, > lpfc_printf_log(phba, KERN_ERR, LOG_LIBDFC, > "2970 Failed to issue SLI_CONFIG ext-buffer " > "mailbox command, rc:x%x\n", rc); > - rc = -EPIPE; > - goto job_error; > + return -EPIPE; and this leaks both the dd_data and pmboxq memory. > } > > /* wait for additional external buffers */ > @@ -4489,14 +4486,6 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, > bsg_job_done(job, bsg_reply->result, > bsg_reply->reply_payload_rcv_len); > return SLI_CONFIG_HANDLED; > - > -job_error: > - if (pmboxq) > - mempool_free(pmboxq, phba->mbox_mem_pool); > - lpfc_bsg_dma_page_free(phba, dmabuf); > - kfree(dd_data); > - > - return rc; > } > > /** all of these errors should cause: lpfc_bsg_write_ebuf_set() to return -Exxx causing lpfc_bsg_handle_sli_cfg_ebuf() to return -Exxx causing lpfc_bsg_handle_sli_cfg_ext() to return -Exxx which causes lpfc_bsg_issue_mbox() to jump to job_done I understand the argument is that issue_mbox deletes them, but.... job_done: checks/frees pmboxq is allocated after the jump so it will be NULL frees dmabuf - which was allocated prior to the jump; is freed in freedlpfc_bsg_handle_sli_cfg_ebuf() but only in a block that returns SLI_CONFIG_HANDLED, which is not the block that invokes lpfc_bsg_write_ebuf_set. So it's valid to delete. Note: there's a special case for SLI_CONFIG_HANDLED which skips over these deletes so it's ok. frees dd_data - which is allocated after the jump so it too will be NULL So - the code is fine. The SLI_CONFIG_HANDLED is a little weird, but the logic is fine. If the patch were added it would leak memory. I take it this was identified by some tool ? -- james
James Smart <jsmart2021@gmail.com> 于2022年11月3日周四 00:37写道： > Minimally, just looking at this one snippet, by returning after the > mempool_alloc() failure, we are leaking the dd_data memory just allocated. > Yes, this is a bad patch. > > @@ -4480,8 +4478,7 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, > > lpfc_printf_log(phba, KERN_ERR, LOG_LIBDFC, > > "2970 Failed to issue SLI_CONFIG ext-buffer " > > "mailbox command, rc:x%x\n", rc); > > - rc = -EPIPE; > > - goto job_error; > > + return -EPIPE; > > and this leaks both the dd_data and pmboxq memory. So Here it is. > > all of these errors should cause: > lpfc_bsg_write_ebuf_set() to return -Exxx > causing lpfc_bsg_handle_sli_cfg_ebuf() to return -Exxx > causing lpfc_bsg_handle_sli_cfg_ext() to return -Exxx > which causes lpfc_bsg_issue_mbox() to jump to job_done > Hi James! Really apprecaite for your reply. I was not sure if it it a really issue. Sorry for the bad patch. > I understand the argument is that issue_mbox deletes them, but.... > > job_done: > checks/frees pmboxq is allocated after the jump so it will be NULL > frees dmabuf - which was allocated prior to the jump; is freed > in freedlpfc_bsg_handle_sli_cfg_ebuf() but only in a block > that returns SLI_CONFIG_HANDLED, which is not the block that > invokes lpfc_bsg_write_ebuf_set. So it's valid to delete. > Note: there's a special case for SLI_CONFIG_HANDLED which skips > over these deletes so it's ok. > frees dd_data - which is allocated after the jump so it too will > be NULL I understood your point. Here is a call chain : lpfc_bsg_issue_mbox->lpfc_bsg_handle_sli_cfg_ext->lpfc_bsg_handle_sli_cfg_ebuf->lpfc_bsg_write_ebuf_set->lpfc_bsg_dma_page_free->kfree(dmabuf) It leads to another kfree in lpfc_bsg_mbox_cmd : job_done: /* common exit for error or job completed inline */ if (pmboxq) mempool_free(pmboxq, phba->mbox_mem_pool); [7] lpfc_bsg_dma_page_free(phba, dmabuf); kfree(dd_data); So the key point is whether phba->mbox_ext_buf_ctx.mboxType can be mbox_wr. If not, just as you illustrated, all is fine. It will get into SLI_CONFIG_HANDLED path and handle dmabuf as expected. But if not, it will have a chance to trigger a double-free bug. I found phda is assigned in lpfc_bsg_mbox_cmd. But I am still not sure about its value. Appreciate if you can help me to understand more about the key condition :) > So - the code is fine. The SLI_CONFIG_HANDLED is a little weird, but > the logic is fine. If the patch were added it would leak memory. > > I take it this was identified by some tool ? > Yes, I found it using Codeql. I didn't have a poc to verify. Best Regards, Zheng Wang
diff --git a/drivers/scsi/lpfc/lpfc_bsg.c b/drivers/scsi/lpfc/lpfc_bsg.c index ac0c7ccf2eae..7362d9c1a50b 100644 --- a/drivers/scsi/lpfc/lpfc_bsg.c +++ b/drivers/scsi/lpfc/lpfc_bsg.c @@ -4439,15 +4439,13 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, dd_data = kmalloc(sizeof(struct bsg_job_data), GFP_KERNEL); if (!dd_data) { - rc = -ENOMEM; - goto job_error; + return -ENOMEM; } /* mailbox command structure for base driver */ pmboxq = mempool_alloc(phba->mbox_mem_pool, GFP_KERNEL); if (!pmboxq) { - rc = -ENOMEM; - goto job_error; + return -ENOMEM; } memset(pmboxq, 0, sizeof(LPFC_MBOXQ_t)); pbuf = (uint8_t *)phba->mbox_ext_buf_ctx.mbx_dmabuf->virt; @@ -4480,8 +4478,7 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, lpfc_printf_log(phba, KERN_ERR, LOG_LIBDFC, "2970 Failed to issue SLI_CONFIG ext-buffer " "mailbox command, rc:x%x\n", rc); - rc = -EPIPE; - goto job_error; + return -EPIPE; } /* wait for additional external buffers */ @@ -4489,14 +4486,6 @@ lpfc_bsg_write_ebuf_set(struct lpfc_hba *phba, struct bsg_job *job, bsg_job_done(job, bsg_reply->result, bsg_reply->reply_payload_rcv_len); return SLI_CONFIG_HANDLED; - -job_error: - if (pmboxq) - mempool_free(pmboxq, phba->mbox_mem_pool); - lpfc_bsg_dma_page_free(phba, dmabuf); - kfree(dd_data); - - return rc; } /**
When error occurs, it frees dmabuf in both lpfc_bsg_write_ebuf_set and lpfc_bsg_issue_mbox. Fix it by removing free code in lpfc_bsg_write_ebuf_set. Reported-by: Zheng Wang <hackerzheng666@gmail.com> Reported-by: Zhuorao Yang <alex000young@gmail.com> Fixes: 7ad20aa9d39a ("[SCSI] lpfc 8.3.24: Extend BSG infrastructure and add link diagnostics") Signed-off-by: Zheng Wang <zyytlz.wz@163.com> --- drivers/scsi/lpfc/lpfc_bsg.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-)