[PATCH 4.14 45/69] scsi: megaraid_sas: fix panic on loading firmware crashdump

From: Greg Kroah-Hartman
Date: Wed Aug 14 2019 - 13:15:11 EST


[ Upstream commit 3b5f307ef3cb5022bfe3c8ca5b8f2114d5bf6c29 ]

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@xxxxxxxxxx>
Acked-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/scsi/megaraid/megaraid_sas_base.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 73acd3e9ded75..8595d83229b77 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -2976,6 +2976,7 @@ megasas_fw_crash_buffer_show(struct device *cdev,
u32 size;
unsigned long buff_addr;
unsigned long dmachunk = CRASH_DMA_BUF_SIZE;
+ unsigned long chunk_left_bytes;
unsigned long src_addr;
unsigned long flags;
u32 buff_offset;
@@ -3001,6 +3002,8 @@ megasas_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] +
--
2.20.1