linux-kernel - [PATCH] scsi: qla4xxx: avoid freeing unallocated dma memory

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Date:   Fri, 22 Mar 2019 15:25:03 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     QLogic-Storage-Upstream@...gic.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Manish Rangankar <mrangankar@...vell.com>,
        Chengguang Xu <cgxu519@....com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] scsi: qla4xxx: avoid freeing unallocated dma memory

Clang -Wuninitialized notices that on is_qla40XX we never allocate
any DMA memory in get_fw_boot_info() but attempt to free it anyway:

drivers/scsi/qla4xxx/ql4_os.c:5915:7: error: variable 'buf_dma' is used uninitialized whenever 'if' condition is false
      [-Werror,-Wsometimes-uninitialized]
                if (!(val & 0x07)) {
                    ^~~~~~~~~~~~~
drivers/scsi/qla4xxx/ql4_os.c:5985:47: note: uninitialized use occurs here
        dma_free_coherent(&ha->pdev->dev, size, buf, buf_dma);
                                                     ^~~~~~~
drivers/scsi/qla4xxx/ql4_os.c:5915:3: note: remove the 'if' if its condition is always true
                if (!(val & 0x07)) {
                ^~~~~~~~~~~~~~~~~~~
drivers/scsi/qla4xxx/ql4_os.c:5885:20: note: initialize the variable 'buf_dma' to silence this warning
        dma_addr_t buf_dma;
                          ^
                           = 0

Skip the call to dma_free_coherent() here.

Fixes: 2a991c215978 ("[SCSI] qla4xxx: Boot from SAN support for open-iscsi")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/scsi/qla4xxx/ql4_os.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
index 16a18d5d856f..daa884fa43f4 100644
--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -5928,7 +5928,7 @@ static int get_fw_boot_info(struct scsi_qla_host *ha, uint16_t ddb_index[])
 		val = rd_nvram_byte(ha, sec_addr);
 		if (val & BIT_7)
 			ddb_index[1] = (val & 0x7f);
-
+		goto exit_boot_info;
 	} else if (is_qla80XX(ha)) {
 		buf = dma_alloc_coherent(&ha->pdev->dev, size,
 					 &buf_dma, GFP_KERNEL);
-- 
2.20.0