From nobody Sat Jul 25 05:17:35 2026 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 24D003F4824 for ; Fri, 17 Jul 2026 11:27:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784287663; cv=none; b=ZI7K6PrRpJZBpQ9nkP2t/HwvMblFxBNnFLUJaMk/a8qD1DmgJDnQ65rbwtLznXGsrdcr7a9Gp561i5jaKzjJfHo19p5k223787/gG3fmzVZubzJq++3a6AiTcmB9L5ELJwobQ5nU8mCh2HAE7ekR6jl+EAd76uXmiYacDEoh7Vw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784287663; c=relaxed/simple; bh=Jhsyyi1JmuZAwzXAR+DzoFURUmwKvQsR0mx/hbCOuqk=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=M2t6BfUB5L7FB8O94Rd3lP0onPo7ZKp8o+OnCvczgpAmNEXggambYkyVJXifyVBDtcUlhBG+4YFCCS6wfJuB73A0ldcoODSClpq4YVe2/syj+LXDNnaMI6owF6qt4Y1u0VgQkBWoix7FCcYUO+jCzAn08bn7kXPfVIqL8wuszvE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de; spf=fail smtp.mailfrom=alpha.franken.de; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=alpha.franken.de Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 9E6BD78E85; Fri, 17 Jul 2026 11:27:33 +0000 (UTC) Authentication-Results: smtp-out1.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 87643779AA; Fri, 17 Jul 2026 11:27:33 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 1qKBIKURWmqWbgAAD6G6ig (envelope-from ); Fri, 17 Jul 2026 11:27:33 +0000 From: Thomas Bogendoerfer To: Oleg Nesterov , James Hogan , Kees Cook , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] MIPS: ptrace: Fix syscall skipping via PTRACE_SYSCALL Date: Fri, 17 Jul 2026 13:27:31 +0200 Message-ID: <20260717112731.59254-1-tsbogend@alpha.franken.de> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spam-Flag: NO X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.991]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[alpha.franken.de:mid,imap1.dmz-prg2.suse.org:helo]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_TLS_ALL(0.00)[] X-Spam-Level: X-Spam-Score: -2.80 Content-Type: text/plain; charset="utf-8" If tracer wanted to skip a syscall return value was always overwritten with -ENOSYS. Fix this by checking against original syscall number and only return -ENOSYS, if it is negative. Fixes: b6318a903d06 ("MIPS/ptrace: Pick up ptrace/seccomp changed syscalls") Signed-off-by: Thomas Bogendoerfer Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- arch/mips/kernel/ptrace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index 3f4c94c88124..87102a03b6ea 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -1321,8 +1321,12 @@ long arch_ptrace(struct task_struct *child, long req= uest, */ asmlinkage long syscall_trace_enter(struct pt_regs *regs) { + long syscall; + user_exit(); =20 + syscall =3D current_thread_info()->syscall; + if (test_thread_flag(TIF_SYSCALL_TRACE)) { if (ptrace_report_syscall_entry(regs)) return -1; @@ -1342,7 +1346,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *r= egs) * Negative syscall numbers are mistaken for rejected syscalls, but * won't have had the return value set appropriately, so we do so now. */ - if (current_thread_info()->syscall < 0) + if (syscall < 0) syscall_set_return_value(current, regs, -ENOSYS, 0); return current_thread_info()->syscall; } --=20 2.51.0