linux-kernel - [PATCH v3] cxl: Fix possible null pointer dereference in read

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Message-Id: <20240714121404.1385892-1-make24@iscas.ac.cn>
Date: Sun, 14 Jul 2024 20:14:04 +0800
From: Ma Ke <make24@...as.ac.cn>
To: fbarrat@...ux.ibm.com,
	ajd@...ux.ibm.com,
	arnd@...db.de,
	gregkh@...uxfoundation.org,
	imunsie@....ibm.com,
	manoj@...ux.vnet.ibm.com,
	mpe@...erman.id.au,
	clombard@...ux.vnet.ibm.com
Cc: linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	Ma Ke <make24@...as.ac.cn>,
	stable@...r.kernel.org
Subject: [PATCH v3] cxl: Fix possible null pointer dereference in read_handle()

In read_handle(), of_get_address() may return NULL which is later
dereferenced. Fix this by adding NULL check.

Based on our customized static analysis tool, extract vulnerability
features[1], then match similar vulnerability features in this function.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit
/?id=2d9adecc88ab678785b581ab021f039372c324cb

Cc: stable@...r.kernel.org
Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
Changes in v3:
- fixed up the changelog text as suggestions.
Changes in v2:
- added an explanation of how the potential vulnerability was discovered,
but not meet the description specification requirements.
---
 drivers/misc/cxl/of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/cxl/of.c b/drivers/misc/cxl/of.c
index bcc005dff1c0..d8dbb3723951 100644
--- a/drivers/misc/cxl/of.c
+++ b/drivers/misc/cxl/of.c
@@ -58,7 +58,7 @@ static int read_handle(struct device_node *np, u64 *handle)
 
 	/* Get address and size of the node */
 	prop = of_get_address(np, 0, &size, NULL);
-	if (size)
+	if (!prop || size)
 		return -EINVAL;
 
 	/* Helper to read a big number; size is in cells (not bytes) */
-- 
2.25.1