From f297dc2364b9a38358ddf92c9812a3d18a102843 Mon Sep 17 00:00:00 2001 From: Xiaomeng Tong Date: Thu, 14 Apr 2022 12:02:31 +0800 Subject: [PATCH] scsi: dc395x: Fix a missing check on list iterator commit 036a45aa587a10fa2abbd50fbd0f6c4cfc44f69f upstream. The bug is here: p->target_id, p->target_lun); The list iterator 'p' will point to a bogus position containing HEAD if the list is empty or no element is found. This case must be checked before any use of the iterator, otherwise it will lead to an invalid memory access. To fix this bug, add a check. Use a new variable 'iter' as the list iterator, and use the original variable 'p' as a dedicated pointer to point to the found element. Link: https://lore.kernel.org/r/20220414040231.2662-1-xiam0nd.tong@gmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Xiaomeng Tong Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/dc395x.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/dc395x.c b/drivers/scsi/dc395x.c index 6cb48ae8e124..d8967bf72ef2 100644 --- a/drivers/scsi/dc395x.c +++ b/drivers/scsi/dc395x.c @@ -3631,10 +3631,19 @@ static struct DeviceCtlBlk *device_alloc(struct AdapterCtlBlk *acb, #endif if (dcb->target_lun != 0) { /* Copy settings */ - struct DeviceCtlBlk *p; - list_for_each_entry(p, &acb->dcb_list, list) - if (p->target_id == dcb->target_id) + struct DeviceCtlBlk *p = NULL, *iter; + + list_for_each_entry(iter, &acb->dcb_list, list) + if (iter->target_id == dcb->target_id) { + p = iter; break; + } + + if (!p) { + kfree(dcb); + return NULL; + } + dprintkdbg(DBG_1, "device_alloc: <%02i-%i> copy from <%02i-%i>\n", dcb->target_id, dcb->target_lun,