The msg subsystem is a common target for exploiting[1][2][3][4][5][6][7]
use-after-free type confusion flaws in the kernel for both read and write
primitives. Avoid having a user-controlled dynamically-size allocation
share the global kmalloc cache by using a separate set of kmalloc buckets
via the kmem_buckets API.
Link: https://blog.hacktivesecurity.com/index.php/2022/06/13/linux-kernel-exploit-development-1day-case-study/ [1]
Link: https://hardenedvault.net/blog/2022-11-13-msg_msg-recon-mitigation-ved/ [2]
Link: https://www.willsroot.io/2021/08/corctf-2021-fire-of-salvation-writeup.html [3]
Link: https://a13xp0p0v.github.io/2021/02/09/CVE-2021-26708.html [4]
Link: https://google.github.io/security-research/pocs/linux/cve-2021-22555/writeup.html [5]
Link: https://zplin.me/papers/ELOISE.pdf [6]
Link: https://syst3mfailure.io/wall-of-perdition/ [7]
Signed-off-by: Kees Cook <[email protected]>
---
Cc: "GONG, Ruiqi" <[email protected]>
Cc: Xiu Jianfeng <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Matteo Rizzo <[email protected]>
Cc: jvoisin <[email protected]>
---
ipc/msgutil.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index d0a0e877cadd..f392f30a057a 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -42,6 +42,17 @@ struct msg_msgseg {
#define DATALEN_MSG ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
#define DATALEN_SEG ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
+static kmem_buckets *msg_buckets __ro_after_init;
+
+static int __init init_msg_buckets(void)
+{
+ msg_buckets = kmem_buckets_create("msg_msg", 0, SLAB_ACCOUNT,
+ sizeof(struct msg_msg),
+ DATALEN_MSG, NULL);
+
+ return 0;
+}
+subsys_initcall(init_msg_buckets);
static struct msg_msg *alloc_msg(size_t len)
{
@@ -50,7 +61,7 @@ static struct msg_msg *alloc_msg(size_t len)
size_t alen;
alen = min(len, DATALEN_MSG);
- msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
+ msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, GFP_KERNEL);
if (msg == NULL)
return NULL;
--
2.34.1