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, 48 insertions, 0 deletions

diff --git a/tools/perf/util/pmu.l b/tools/perf/util/pmu.l
new file mode 100644
index 000000000..67b247be6
--- /dev/null
+++ b/tools/perf/util/pmu.l
@@ -0,0 +1,48 @@
+%option prefix="perf_pmu_"
+%option reentrant
+%option bison-bridge
+
+%{
+#include <stdlib.h>
+#include <linux/bitops.h>
+#include "pmu.h"
+#include "pmu-bison.h"
+
+char *perf_pmu_get_text(yyscan_t yyscanner);
+YYSTYPE *perf_pmu_get_lval(yyscan_t yyscanner);
+
+static int value(yyscan_t scanner, int base)
+{
+	YYSTYPE *yylval = perf_pmu_get_lval(scanner);
+	char *text = perf_pmu_get_text(scanner);
+	long num;
+
+	errno = 0;
+	num = strtoul(text, NULL, base);
+	if (errno)
+		return PP_ERROR;
+
+	yylval->num = num;
+	return PP_VALUE;
+}
+
+%}
+
+num_dec         [0-9]+
+
+%%
+
+{num_dec}	{ return value(yyscanner, 10); }
+config		{ return PP_CONFIG; }
+-		{ return '-'; }
+:		{ return ':'; }
+,		{ return ','; }
+.		{ ; }
+\n		{ ; }
+
+%%
+
+int perf_pmu_wrap(void *scanner __maybe_unused)
+{
+	return 1;
+}