linux-kernel - [PATCH 3.16 009/132] scsi: qla4xxx: avoid freeing unallocated dma memory

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Date:   Fri, 20 Sep 2019 15:23:35 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Nathan Chancellor" <natechancellor@...il.com>,
        "Arnd Bergmann" <arnd@...db.de>
Subject: [PATCH 3.16 009/132] scsi: qla4xxx: avoid freeing unallocated dma
 memory

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit 608f729c31d4caf52216ea00d20092a80959256d upstream.

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>
Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/scsi/qla4xxx/ql4_os.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -5923,7 +5923,7 @@ static int get_fw_boot_info(struct scsi_
 		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);