staging: rtl8723bs: fix OOB read in rtw_action_frame_parse()grafted

rtw_action_frame_parse() takes a frame_len parameter but never
actually checks it before indexing into the frame body:

	const u8 *frame_body = frame + sizeof(struct ieee80211_hdr_3addr);
	...
	c = frame_body[0];
	...
	a = frame_body[1];

frame_body already points 24 bytes (sizeof(struct
ieee80211_hdr_3addr)) into frame, so reading frame_body[0] and
frame_body[1] requires frame_len >= 26. A management action frame
shorter than that (e.g. exactly 24 bytes, the minimum a malicious
peer can send) causes a 1-2 byte out-of-bounds read.

This is reachable from rtw_cfg80211_monitor_if_xmit_entry() and
cfg80211_rtw_mgmt_tx() in ioctl_cfg80211.c, both of which pass
attacker/user-influenced frame buffers and lengths straight through.

Add the missing length check before frame_body is dereferenced.

Fixes: 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
Link: https://patch.msgid.link/20260728125456.32359-3-meatuni001@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 108 insertions, 0 deletions

diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c
new file mode 100644
index 000000000..5ef9a0466
--- /dev/null
+++ b/fs/nfsd/auth.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */
+
+#include <linux/sched.h>
+#include "nfsd.h"
+#include "export.h"
+#include "auth.h"
+
+int nfsexp_flags(struct svc_cred *cred, struct svc_export *exp)
+{
+	struct exp_flavor_info *f;
+	struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
+
+	for (f = exp->ex_flavors; f < end; f++) {
+		if (f->pseudoflavor == cred->cr_flavor)
+			return f->flags;
+	}
+	return exp->ex_flags;
+
+}
+
+int nfsd_setuser(struct svc_cred *cred, struct svc_export *exp)
+{
+	struct group_info *rqgi;
+	struct group_info *gi;
+	struct cred *new;
+	int i;
+	int flags = nfsexp_flags(cred, exp);
+
+	/* discard any old override before preparing the new set */
+	put_cred(revert_creds(get_cred(current_real_cred())));
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+
+	new->fsuid = cred->cr_uid;
+	new->fsgid = cred->cr_gid;
+
+	rqgi = cred->cr_group_info;
+
+	if (flags & NFSEXP_ALLSQUASH) {
+		new->fsuid = exp->ex_anon_uid;
+		new->fsgid = exp->ex_anon_gid;
+		gi = groups_alloc(0);
+		if (!gi)
+			goto oom;
+	} else if (flags & NFSEXP_ROOTSQUASH) {
+		if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
+			new->fsuid = exp->ex_anon_uid;
+		if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
+			new->fsgid = exp->ex_anon_gid;
+
+		gi = groups_alloc(rqgi->ngroups);
+		if (!gi)
+			goto oom;
+
+		for (i = 0; i < rqgi->ngroups; i++) {
+			if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
+				gi->gid[i] = exp->ex_anon_gid;
+			else
+				gi->gid[i] = rqgi->gid[i];
+		}
+
+		/* Each thread allocates its own gi, no race */
+		groups_sort(gi);
+	} else {
+		gi = get_group_info(rqgi);
+	}
+
+	if (uid_eq(new->fsuid, INVALID_UID))
+		new->fsuid = exp->ex_anon_uid;
+	if (gid_eq(new->fsgid, INVALID_GID))
+		new->fsgid = exp->ex_anon_gid;
+
+	set_groups(new, gi);
+	put_group_info(gi);
+
+	if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
+		new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
+	else
+		new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
+							new->cap_permitted);
+	put_cred(override_creds(new));
+	return 0;
+
+oom:
+	abort_creds(new);
+	return -ENOMEM;
+}
+
+/**
+ * nfsd_user_namespace - Get user_namespace in effect for an RPC request
+ * @rqstp: RPC execution context
+ *
+ * xpt_cred is set once at transport creation and never modified. The
+ * transport itself is reference-counted during request processing, so
+ * no explicit reference on the namespace is necessary.
+ *
+ * Return: the user_namespace from the transport credential, or
+ * init_user_ns if no credential was set. The returned namespace pointer
+ * is valid for the duration of the RPC request.
+ */
+struct user_namespace *nfsd_user_namespace(const struct svc_rqst *rqstp)
+{
+	const struct cred *cred = rqstp->rq_xprt->xpt_cred;
+
+	return cred ? cred->user_ns : &init_user_ns;
+}