2023-06-23 02:57:05

by Jiasheng Jiang

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 <[email protected]>
---
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

2023-10-12 16:49:01

by Kees Cook

Subject: Re: [PATCH v3] pstore/platform: Add check for kstrdup

On Fri, 23 Jun 2023 10:27:06 +0800, Jiasheng Jiang wrote:
> Add check for the return value of kstrdup() and return the error
> if it fails in order to avoid NULL pointer dereference.
>
>

Applied to for-next/pstore, thanks!

[1/1] pstore/platform: Add check for kstrdup
https://git.kernel.org/kees/c/a19d48f7c5d5

Take care,

--
Kees Cook