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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Junxiao Bi <junxiao.bi@oracle.com>,
        Sumit Saxena <sumit.saxena@broadcom.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 026/103] scsi: megaraid_sas: fix panic on loading firmware crashdump
Date:   Thu, 22 Aug 2019 10:18:14 -0700
Message-Id: <20190822171729.910717938@linuxfoundation.org>
In-Reply-To: <20190822171728.445189830@linuxfoundation.org>
References: <20190822171728.445189830@linuxfoundation.org>
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[ 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@oracle.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 5b1c37e3913cd..d90693b2767fd 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -2847,6 +2847,7 @@ 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;
@@ -2872,6 +2873,8 @@ 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