From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0F4DA45517D for ; Thu, 17 Sep 2026 16:26:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662393; cv=none; b=Q8KCnaLnPHphKz8MqBMD7VqF0pdkxyMWUgKyvFHpDo1mcf/dnMh/giyOc8pKlFde0HG/Y8fi5fPhnfMiKrP+lnBth8SNI1txAfkCKxL3iCidHpl9lfQsa9J9YEp5IAeKbEYbOxCrK2UaUjzVpSwTIzVXIy3KFvswuqq8rfZo77s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662393; c=relaxed/simple; bh=RmAnVoJAJd1+enTSTq8S1ovWq9s12vERI89AcxEtSfA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=HoG4YY5CxOFYF4X0kaZyyc5Vm9bn3HCqAZz0pEZJpbVwH6vB7Kw8mRVFOWcaTQZIqBYQs1P2COFc27ToDyB/4hshpZtW4kbuNp8okip09T/Arfo2OPuBVw1vYFXqUS4zjakutOcS6ZGjUQqqOB3OVPNn+dt9mL0fdUxp2okQkzU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fXre413m; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fXre413m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D4311F00893; Thu, 17 Sep 2026 16:26:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789662391; bh=YuFQowUj45y6l9HKnebVNBEmbTtkU9HqQxUNzfo4Fi8=; h=From:To:Cc:Subject:Date:Reply-To; b=fXre413ml4fcwlMEnBedqyjxbUMmvtQIJPOS+6jAIaAiXuofoIxUmf+vayeQVJv+X DDRxm/3gS52PEeEx8ghMiyMSAuYm+WCmazNX2anCIj71CCmgp4s3f3jdvKovzw2Vyu 09m8Ewcd8BEPxVZ5MhPOd6oqs3a+hfyMfgMJCEVg= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-90339: powerpc/syscall: Fix syscall skip handling for seccomp and ptrace Date: Thu, 17 Sep 2026 17:12:49 +0100 Message-ID: <2026091702-CVE-2026-90339-437d@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3377; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=06S1aPP+VD7Q+26v5sqw82aFcVCInDxNm2wOrsZ4ppA=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBOb9Wrwqujzj/XOBaCPTeBkz3tTbLMn2FQ/01La/S lnQ/te5I5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACbC78owz4qn13Pd+uDXb57Y BOrfWNCqs/LmWYbZ7GdjwsSLFHU2vtr/ba7ABPbd9xa8AQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: powerpc/syscall: Fix syscall skip handling for seccomp and ptrace After enabling GENERIC_ENTRY on PowerPC, syscall_enter_from_user_mode() returns -1 as a sentinel to signal that seccomp or ptrace has intercepted the syscall and already set a return value via syscall_set_return_value(). system_call_exception() was not handling this sentinel, and since -1UL is >= NR_syscalls, the code fell into the out-of-range path and returned -ENOSYS, overwriting the errno already placed in regs->gpr[3]. The naive fix of checking r0 == -1L before the NR_syscalls bounds check is ambiguous: a user legitimately calling syscall(-1) also produces r0 == -1L, and a tracer intercepting such a call would have its injected return value silently discarded. Fix this by introducing a thread flag that is set whenever syscall_set_return_value() explicitly updates the return value. In system_call_exception(), check and clear this flag before dispatching the syscall, and return the preset value directly when it is present. This ensures that an explicitly supplied return value always suppresses syscall execution, regardless of the syscall number. This handles all seccomp actions correctly: - SECCOMP_RET_ERRNO, SECCOMP_RET_TRACE (no tracer), SECCOMP_RET_USER_NOTIF: all call syscall_set_return_value(), flag is set, injected value returned. - SECCOMP_RET_TRAP, SECCOMP_RET_KILL: call syscall_rollback() and deliver a signal; flag is not set, but the process is dying so the return value is irrelevant. The fix covers both ppc32 and ppc64 with no #ifdefs. The Linux kernel CVE team has assigned CVE-2026-90339 to this issue. Affected and fixed versions =========================== Issue introduced in 7.2 with commit bee25f97ad24641df55cb3887eb5bfcb2b9d8fbc and fixed in 7.2.6 with commit 19b54740e2e1102c7d48553d9e0347c1f6af22b0 Issue introduced in 7.2 with commit bee25f97ad24641df55cb3887eb5bfcb2b9d8fbc and fixed in 7.3-rc1 with commit 69cb2be898be6d5826cacd1a628f6945a24480b6 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-90339 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: arch/powerpc/include/asm/syscall.h arch/powerpc/include/asm/thread_info.h arch/powerpc/kernel/syscall.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/19b54740e2e1102c7d48553d9e0347c1f6af22b0 https://git.kernel.org/stable/c/69cb2be898be6d5826cacd1a628f6945a24480b6