scsi: megaraid_sas: fix panic on loading firmware crashdump

While loading fw crashdump in function fw_crash_buffer_show(), left bytes
in one dma chunk was not checked, if copying size over it, overflow access
will cause kernel panic.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 2590746..f9f0793 100644 (file)
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -3163,6 +3163,7 @@ fw_crash_buffer_show(struct device *cdev,
                (struct megasas_instance *) shost->hostdata;
        u32 size;
        unsigned long dmachunk = CRASH_DMA_BUF_SIZE;
+       unsigned long chunk_left_bytes;
        unsigned long src_addr;
        unsigned long flags;
        u32 buff_offset;
@@ -3186,6 +3187,8 @@ fw_crash_buffer_show(struct device *cdev,
        }
 
        size = (instance->fw_crash_buffer_size * dmachunk) - buff_offset;
+       chunk_left_bytes = dmachunk - (buff_offset % dmachunk);
+       size = (size > chunk_left_bytes) ? chunk_left_bytes : size;
        size = (size >= PAGE_SIZE) ? (PAGE_SIZE - 1) : size;
 
        src_addr = (unsigned long)instance->crash_buf[buff_offset / dmachunk] +