From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8AAF83B4EA3; Mon, 23 Mar 2026 14:06:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274795; cv=none; b=QrcbD8SUo1UKh6ugocNJ8h7TtFPUvgoS51XxVBUxfylaNZ9ZpvMMlL6EtEdTPZ2duIMP/d/TJAQ07IKh33OAFMbm/AR7QSOw55X7jaDfSP3vfhGSHBwDS2TR43pm/rn3gI5rEVQzQCzCYi6oGpaso2U4CCAdV0NT7/7K0yNTsiQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774274795; c=relaxed/simple; bh=DwKz7VHQKjqqSgmxby1qG+/w3lZOnDDhYBI7YtttazM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DZ1dmqgiN2JwBJ+TKccd09u8Dy+STFp3sZlcoiWl8zNJKf+mbMcZZxrkEd8G97cHIcpPU7p3yD8Sc+puKBZ7NGKelxJBll2Qm6gMJNWA5xNARlFOtCTBN9tR+VDdSgSpC2lXkDULSFmHyzId7hlQePUYmswaT3rqe9qM5mxnuFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=12dcSWeL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="12dcSWeL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04EC5C4CEF7; Mon, 23 Mar 2026 14:06:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774274795; bh=DwKz7VHQKjqqSgmxby1qG+/w3lZOnDDhYBI7YtttazM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=12dcSWeLNlRJiyjJHdmXiTqyLLwvI1ZbQUAt/B1/D+ULOY+1mpLxen13Q0zdvp8th xwFOblvQw7qjkWX36zaz8kPdFKIwK+9w+Cg8nD0AF5g3aVamQUwyb/sA8Sp8JjusXz aWFv/8Nvot4lTSLRq/FF58Dr4jI5Cw/OreARGLH0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+feb9ce36a95341bb47a4@syzkaller.appspotmail.com, Kuniyuki Iwashima , Johannes Berg , Sasha Levin Subject: [PATCH 6.18 110/212] wifi: mac80211: Fix static_branch_dec() underflow for aql_disable. Date: Mon, 23 Mar 2026 14:45:31 +0100 Message-ID: <20260323134507.258344129@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134503.770111826@linuxfoundation.org> References: <20260323134503.770111826@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit b94ae8e0d5fe1bdbbfdc3854ff6ce98f6876a828 ] syzbot reported static_branch_dec() underflow in aql_enable_write(). [0] The problem is that aql_enable_write() does not serialise concurrent write()s to the debugfs. aql_enable_write() checks static_key_false(&aql_disable.key) and later calls static_branch_inc() or static_branch_dec(), but the state may change between the two calls. aql_disable does not need to track inc/dec. Let's use static_branch_enable() and static_branch_disable(). [0]: val == 0 WARNING: kernel/jump_label.c:311 at __static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311, CPU#0: syz.1.3155/20288 Modules linked in: CPU: 0 UID: 0 PID: 20288 Comm: syz.1.3155 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:__static_key_slow_dec_cpuslocked.part.0+0x107/0x120 kernel/jump_label.c:311 Code: f2 c9 ff 5b 5d c3 cc cc cc cc e8 54 f2 c9 ff 48 89 df e8 ac f9 ff ff eb ad e8 45 f2 c9 ff 90 0f 0b 90 eb a2 e8 3a f2 c9 ff 90 <0f> 0b 90 eb 97 48 89 df e8 5c 4b 33 00 e9 36 ff ff ff 0f 1f 80 00 RSP: 0018:ffffc9000b9f7c10 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffffff9b3e5d40 RCX: ffffffff823c57b4 RDX: ffff8880285a0000 RSI: ffffffff823c5846 RDI: ffff8880285a0000 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000000a R13: 1ffff9200173ef88 R14: 0000000000000001 R15: ffffc9000b9f7e98 FS: 00007f530dd726c0(0000) GS:ffff8881245e3000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000001140 CR3: 000000007cc4a000 CR4: 00000000003526f0 Call Trace: __static_key_slow_dec_cpuslocked kernel/jump_label.c:297 [inline] __static_key_slow_dec kernel/jump_label.c:321 [inline] static_key_slow_dec+0x7c/0xc0 kernel/jump_label.c:336 aql_enable_write+0x2b2/0x310 net/mac80211/debugfs.c:343 short_proxy_write+0x133/0x1a0 fs/debugfs/file.c:383 vfs_write+0x2aa/0x1070 fs/read_write.c:684 ksys_pwrite64 fs/read_write.c:793 [inline] __do_sys_pwrite64 fs/read_write.c:801 [inline] __se_sys_pwrite64 fs/read_write.c:798 [inline] __x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:798 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f530cf9aeb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f530dd72028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 RAX: ffffffffffffffda RBX: 00007f530d215fa0 RCX: 00007f530cf9aeb9 RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000010 RBP: 00007f530d008c1f R08: 0000000000000000 R09: 0000000000000000 R10: 4200000000000005 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f530d216038 R14: 00007f530d215fa0 R15: 00007ffde89fb978 Fixes: e908435e402a ("mac80211: introduce aql_enable node in debugfs") Reported-by: syzbot+feb9ce36a95341bb47a4@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69a8979e.a70a0220.b118c.0025.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260306072405.3649474-1-kuniyu@google.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- net/mac80211/debugfs.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c index d02f07368c511..687a66cd49433 100644 --- a/net/mac80211/debugfs.c +++ b/net/mac80211/debugfs.c @@ -320,7 +320,6 @@ static ssize_t aql_enable_read(struct file *file, char __user *user_buf, static ssize_t aql_enable_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { - bool aql_disabled = static_key_false(&aql_disable.key); char buf[3]; size_t len; @@ -335,15 +334,12 @@ static ssize_t aql_enable_write(struct file *file, const char __user *user_buf, if (len > 0 && buf[len - 1] == '\n') buf[len - 1] = 0; - if (buf[0] == '0' && buf[1] == '\0') { - if (!aql_disabled) - static_branch_inc(&aql_disable); - } else if (buf[0] == '1' && buf[1] == '\0') { - if (aql_disabled) - static_branch_dec(&aql_disable); - } else { + if (buf[0] == '0' && buf[1] == '\0') + static_branch_enable(&aql_disable); + else if (buf[0] == '1' && buf[1] == '\0') + static_branch_disable(&aql_disable); + else return -EINVAL; - } return count; } -- 2.51.0