[PATCH net] bnxt_en: Fix memory fault in bnxt_ethtool_init()

[Michael Chan <michael.chan@broadcom.com>]

From: Vasundhara Volam <vasundhara-v.volam@broadcom.com>

In some firmware images, the length of BNX_DIR_TYPE_PKG_LOG nvram type
could be greater than the fixed buffer length of 4096 bytes allocated by
the driver.  This was causing HWRM_NVM_READ to copy more data to the buffer
than the allocated size, causing general protection fault.

Fix the issue by allocating the exact buffer length returned by
HWRM_NVM_FIND_DIR_ENTRY, instead of 4096.  Move the kzalloc() call
into the bnxt_get_pkgver() function.

Fixes: 3ebf6f0a09a2 ("bnxt_en: Add installed-package firmware version reporting via Ethtool GDRVINFO")
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c  | 49 ++++++++++++----------
 drivers/net/ethernet/broadcom/bnxt/bnxt_nvm_defs.h |  2 -
 2 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 1f622ca..8ba14ae 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -1927,22 +1927,39 @@ static char *bnxt_parse_pkglog(int desired_field, u8 *data, size_t datalen)
 	return retval;
 }
 
-static char *bnxt_get_pkgver(struct net_device *dev, char *buf, size_t buflen)
+static void bnxt_get_pkgver(struct net_device *dev)
 {
+	struct bnxt *bp = netdev_priv(dev);
 	u16 index = 0;
-	u32 datalen;
+	char *pkgver;
+	u32 pkglen;
+	u8 *pkgbuf;
+	int len;
 
 	if (bnxt_find_nvram_item(dev, BNX_DIR_TYPE_PKG_LOG,
 				 BNX_DIR_ORDINAL_FIRST, BNX_DIR_EXT_NONE,
-				 &index, NULL, &datalen) != 0)
-		return NULL;
+				 &index, NULL, &pkglen) != 0)
+		return;
 
-	memset(buf, 0, buflen);
-	if (bnxt_get_nvram_item(dev, index, 0, datalen, buf) != 0)
-		return NULL;
+	pkgbuf = kzalloc(pkglen, GFP_KERNEL);
+	if (!pkgbuf) {
+		dev_err(&bp->pdev->dev, "Unable to allocate memory for pkg version, length = %u\n",
+			pkglen);
+		return;
+	}
+
+	if (bnxt_get_nvram_item(dev, index, 0, pkglen, pkgbuf))
+		goto err;
 
-	return bnxt_parse_pkglog(BNX_PKG_LOG_FIELD_IDX_PKG_VERSION, buf,
-		datalen);
+	pkgver = bnxt_parse_pkglog(BNX_PKG_LOG_FIELD_IDX_PKG_VERSION, pkgbuf,
+				   pkglen);
+	if (pkgver && *pkgver != 0 && isdigit(*pkgver)) {
+		len = strlen(bp->fw_ver_str);
+		snprintf(bp->fw_ver_str + len, FW_VER_STR_LEN - len - 1,
+			 "/pkg %s", pkgver);
+	}
+err:
+	kfree(pkgbuf);
 }
 
 static int bnxt_get_eeprom(struct net_device *dev,
@@ -2615,22 +2632,10 @@ void bnxt_ethtool_init(struct bnxt *bp)
 	struct hwrm_selftest_qlist_input req = {0};
 	struct bnxt_test_info *test_info;
 	struct net_device *dev = bp->dev;
-	char *pkglog;
 	int i, rc;
 
-	pkglog = kzalloc(BNX_PKG_LOG_MAX_LENGTH, GFP_KERNEL);
-	if (pkglog) {
-		char *pkgver;
-		int len;
+	bnxt_get_pkgver(dev);
 
-		pkgver = bnxt_get_pkgver(dev, pkglog, BNX_PKG_LOG_MAX_LENGTH);
-		if (pkgver && *pkgver != 0 && isdigit(*pkgver)) {
-			len = strlen(bp->fw_ver_str);
-			snprintf(bp->fw_ver_str + len, FW_VER_STR_LEN - len - 1,
-				 "/pkg %s", pkgver);
-		}
-		kfree(pkglog);
-	}
 	if (bp->hwrm_spec_code < 0x10704 || !BNXT_SINGLE_PF(bp))
 		return;
 
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_nvm_defs.h b/drivers/net/ethernet/broadcom/bnxt/bnxt_nvm_defs.h
index 73f2249..8344481 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_nvm_defs.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_nvm_defs.h
@@ -59,8 +59,6 @@ enum bnxt_nvm_directory_type {
 #define BNX_DIR_ATTR_NO_CHKSUM			(1 << 0)
 #define BNX_DIR_ATTR_PROP_STREAM		(1 << 1)
 
-#define BNX_PKG_LOG_MAX_LENGTH			4096
-
 enum bnxnvm_pkglog_field_index {
 	BNX_PKG_LOG_FIELD_IDX_INSTALLED_TIMESTAMP	= 0,
 	BNX_PKG_LOG_FIELD_IDX_PKG_DESCRIPTION		= 1,
-- 
1.8.3.1