linux-hardening - [PATCH v3] pstore/platform: Add check for kstrdup

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Message-Id: <20230623022706.32125-1-jiasheng@iscas.ac.cn>
Date:   Fri, 23 Jun 2023 10:27:06 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     keescook@...omium.org
Cc:     tony.luck@...el.com, gpiccoli@...lia.com,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v3] pstore/platform: Add check for kstrdup

Add check for the return value of kstrdup() and return the error
if it fails in order to avoid NULL pointer dereference.

Fixes: 563ca40ddf40 ("pstore/platform: Switch pstore_info::name to const")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog:

v2 -> v3:

1. Add kfree() in the later error handling.

v1 -> v2:

1. Allocate a copy earlier.
---
 fs/pstore/platform.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index cbc0b468c1ab..15cefe268ffd 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -573,6 +573,8 @@ static int pstore_write_user_compat(struct pstore_record *record,
  */
 int pstore_register(struct pstore_info *psi)
 {
+	char *new_backend;
+
 	if (backend && strcmp(backend, psi->name)) {
 		pr_warn("backend '%s' already in use: ignoring '%s'\n",
 			backend, psi->name);
@@ -593,11 +595,16 @@ int pstore_register(struct pstore_info *psi)
 		return -EINVAL;
 	}
 
+	new_backend = kstrdup(psi->name, GFP_KERNEL);
+	if (!new_backend)
+		return -ENOMEM;
+
 	mutex_lock(&psinfo_lock);
 	if (psinfo) {
 		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
 			psinfo->name, psi->name);
 		mutex_unlock(&psinfo_lock);
+		kfree(new_backend);
 		return -EBUSY;
 	}
 
@@ -630,7 +637,7 @@ int pstore_register(struct pstore_info *psi)
 	 * Update the module parameter backend, so it is visible
 	 * through /sys/module/pstore/parameters/backend
 	 */
-	backend = kstrdup(psi->name, GFP_KERNEL);
+	backend = new_backend;
 
 	pr_info("Registered %s as persistent store backend\n", psi->name);
 
-- 
2.25.1