From ff917923f4fb9c83717ba135ee47d7e4c1567bb7 Mon Sep 17 00:00:00 2001 From: Muhammad Bilal Date: Tue, 28 Jul 2026 17:54:55 +0500 Subject: staging: rtl8723bs: fix OOB read in rtw_action_frame_parse() 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 Link: https://patch.msgid.link/20260728125456.32359-3-meatuni001@gmail.com Signed-off-by: Greg Kroah-Hartman --- lib/cmpxchg-emu.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 lib/cmpxchg-emu.c (limited to 'lib/cmpxchg-emu.c') diff --git a/lib/cmpxchg-emu.c b/lib/cmpxchg-emu.c new file mode 100644 index 000000000..27f6f97cb --- /dev/null +++ b/lib/cmpxchg-emu.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Emulated 1-byte cmpxchg operation for architectures lacking direct + * support for this size. This is implemented in terms of 4-byte cmpxchg + * operations. + * + * Copyright (C) 2024 Paul E. McKenney. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +union u8_32 { + u8 b[4]; + u32 w; +}; + +/* Emulate one-byte cmpxchg() in terms of 4-byte cmpxchg. */ +uintptr_t cmpxchg_emu_u8(volatile u8 *p, uintptr_t old, uintptr_t new) +{ + u32 *p32 = (u32 *)(((uintptr_t)p) & ~0x3); + int i = ((uintptr_t)p) & 0x3; + union u8_32 old32; + union u8_32 new32; + u32 ret; + + ret = READ_ONCE(*p32); + do { + old32.w = ret; + if (old32.b[i] != old) + return old32.b[i]; + new32.w = old32.w; + new32.b[i] = new; + instrument_atomic_read_write(p, 1); + ret = data_race(cmpxchg(p32, old32.w, new32.w)); // Overridden above. + } while (ret != old32.w); + return old; +} +EXPORT_SYMBOL_GPL(cmpxchg_emu_u8); -- cgit v1.3.1