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/dec_and_lock.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 lib/dec_and_lock.c (limited to 'lib/dec_and_lock.c') diff --git a/lib/dec_and_lock.c b/lib/dec_and_lock.c new file mode 100644 index 000000000..8c7c398fd --- /dev/null +++ b/lib/dec_and_lock.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +/* + * This is an implementation of the notion of "decrement a + * reference count, and return locked if it decremented to zero". + * + * NOTE NOTE NOTE! This is _not_ equivalent to + * + * if (atomic_dec_and_test(&atomic)) { + * spin_lock(&lock); + * return 1; + * } + * return 0; + * + * because the spin-lock and the decrement must be + * "atomic". + */ +int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock) +{ + /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ + if (atomic_add_unless(atomic, -1, 1)) + return 0; + + /* Otherwise do it the slow way */ + spin_lock(lock); + if (atomic_dec_and_test(atomic)) + return 1; + spin_unlock(lock); + return 0; +} + +EXPORT_SYMBOL(atomic_dec_and_lock); + +int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock, + unsigned long *flags) +{ + /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ + if (atomic_add_unless(atomic, -1, 1)) + return 0; + + /* Otherwise do it the slow way */ + spin_lock_irqsave(lock, *flags); + if (atomic_dec_and_test(atomic)) + return 1; + spin_unlock_irqrestore(lock, *flags); + return 0; +} +EXPORT_SYMBOL(_atomic_dec_and_lock_irqsave); + +int atomic_dec_and_raw_lock(atomic_t *atomic, raw_spinlock_t *lock) +{ + /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ + if (atomic_add_unless(atomic, -1, 1)) + return 0; + + /* Otherwise do it the slow way */ + raw_spin_lock(lock); + if (atomic_dec_and_test(atomic)) + return 1; + raw_spin_unlock(lock); + return 0; +} +EXPORT_SYMBOL(atomic_dec_and_raw_lock); + +int _atomic_dec_and_raw_lock_irqsave(atomic_t *atomic, raw_spinlock_t *lock, + unsigned long *flags) +{ + /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */ + if (atomic_add_unless(atomic, -1, 1)) + return 0; + + /* Otherwise do it the slow way */ + raw_spin_lock_irqsave(lock, *flags); + if (atomic_dec_and_test(atomic)) + return 1; + raw_spin_unlock_irqrestore(lock, *flags); + return 0; +} +EXPORT_SYMBOL(_atomic_dec_and_raw_lock_irqsave); -- cgit v1.3.1