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/math/reciprocal_div.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 lib/math/reciprocal_div.c (limited to 'lib/math/reciprocal_div.c') diff --git a/lib/math/reciprocal_div.c b/lib/math/reciprocal_div.c new file mode 100644 index 000000000..6cb4adbb8 --- /dev/null +++ b/lib/math/reciprocal_div.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include + +#include + +/* + * For a description of the algorithm please have a look at + * include/linux/reciprocal_div.h + */ + +struct reciprocal_value reciprocal_value(u32 d) +{ + struct reciprocal_value R; + u64 m; + int l; + + l = fls(d - 1); + m = ((1ULL << 32) * ((1ULL << l) - d)); + do_div(m, d); + ++m; + R.m = (u32)m; + R.sh1 = min(l, 1); + R.sh2 = max(l - 1, 0); + + return R; +} +EXPORT_SYMBOL(reciprocal_value); + +struct reciprocal_value_adv reciprocal_value_adv(u32 d, u8 prec) +{ + struct reciprocal_value_adv R; + u32 l, post_shift; + u64 mhigh, mlow; + + /* ceil(log2(d)) */ + l = fls(d - 1); + /* NOTE: mlow/mhigh could overflow u64 when l == 32. This case needs to + * be handled before calling "reciprocal_value_adv", please see the + * comment at include/linux/reciprocal_div.h. + */ + WARN(l == 32, + "ceil(log2(0x%08x)) == 32, %s doesn't support such divisor", + d, __func__); + post_shift = l; + mlow = 1ULL << (32 + l); + do_div(mlow, d); + mhigh = (1ULL << (32 + l)) + (1ULL << (32 + l - prec)); + do_div(mhigh, d); + + for (; post_shift > 0; post_shift--) { + u64 lo = mlow >> 1, hi = mhigh >> 1; + + if (lo >= hi) + break; + + mlow = lo; + mhigh = hi; + } + + R.m = (u32)mhigh; + R.sh = post_shift; + R.exp = l; + R.is_wide_m = mhigh > U32_MAX; + + return R; +} +EXPORT_SYMBOL(reciprocal_value_adv); -- cgit v1.3.1