From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792759193; b=NSPyGX9WHHf41v+zFchsgbf5LhgXsrW2VMrdlnKgbsBj/INIb6Iz40X2yI0WxfPiBs4r j7R3MHF2zeaWEOtCeqibdooJTKj8e3rAo7b1vO2L02kbklSiG59ntt/VIsoKgmyqJJrxo +vTxkMFhwMQ8ZkQSnyPsCw7v0WjXYjCnpKHVX90eOjbkoEuaQfmlE8w/udwDU19n2GgIw TllOje8JzGZmnN8PbcfPAbtF7FCkHIv1pLBy6SYyqEOhf4e760ZeX8ko7ddKJuVEetm3P XBaXUzSApX8L6dxrkiaH56fHmp2QUH1Vybn3yLqkMxzdiZ22SbrFO91WBtkJ/DakcMw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792759193; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: Reply-To:MIME-Version:Lines:X-Developer-Signature:X-Developer-Key: Content-Transfer-Encoding; bh=SW159TejURV4SrmkMjeGEIakIDOTGoajzwo0Qw0J5ug=; b=AX8enMjfhVN/LH+ZHB6mc+IGERE3FNBlsNp7GzOhZUZ663hnDM1C6alzRR9Ka2JdoIK1 7SNoOMVbC8jstyYa7feihH8tYgXkp800LVA0xcKIcvQgEx7fvyDtk7EQ6AWwnFRyLwj8y MuzZASib1AkHJlrT5NPq6hAdaqxkqGhXfNyKLsDUlp+9ChR8RndGCp6I7mrYhVgMuWf5u z1bnawFuUGoqdOwUNW8PKMZwYuYUXAV6lmbZ7FarPoM7VvZuq2rXjm5IZ/KlCS5X7k/gs Q/B6Nq76OEihjfx0oTKuFWZrHOBR2ULkB95WEFgKTgYVZmjb9x7XUBiVGCGfsXZ77nw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=srGepkTR; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8790C606A31A for ; Fri, 23 Oct 2026 12:39:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=srGepkTR Received: by smtp.kernel.org (Postfix) with ESMTPSA id A80D51F01825; Fri, 23 Oct 2026 12:39:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792759193; bh=SW159TejURV4SrmkMjeGEIakIDOTGoajzwo0Qw0J5ug=; h=From:To:Cc:Subject:Date:Reply-To; b=srGepkTRLmeNEAR9jpSolVfS+/zJ8hfve8hxohigMoK0PzfbhVis+wa+JEwPzwtfw V3/tl8OI0LN5MKptv6kl3A/foQUVckdLrDJ/glzEdzFrzOSrzyp1VAZggpusZU/aYD HPutwpU5y9uKeM005Kkn8RKI8fKUi9+tJTwzsYb0= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-99016: riscv: futex: untag the user pointer before the atomic access Date: Fri, 23 Oct 2026 14:20:18 +0200 Message-ID: <2026102321-CVE-2026-99016-4e82@gregkh> X-Mailer: git-send-email 2.56.0 Reply-To: , X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3329; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=xDHmt1nU9J5iP+XJQPVNkIb0fvdnwi1SWfMbHIO16xg=; b=owGbwMvMwCRo6H6F97bub03G02pJDFm3A07e5azZHb77v0ILy9UZ81Z5a9ko7em3Mcp8wPorq rhx/crejlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZhI2SmGBWuE1f9MfVP64eQZ LptNzGHVXObSVgzz1B3UXr/i3D7Vf/XfRpYLDgXX171YDgA= 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: riscv: futex: untag the user pointer before the atomic access access_ok() checks untagged_addr(uaddr), but arch_futex_atomic_op_inuser() and futex_atomic_cmpxchg_inatomic() hand the raw uaddr to the inline asm amoswap/amoadd/.../lr.w+sc.w through the "+m" (*uaddr) operand. When the tagged address ABI is enabled (CONFIG_RISCV_ISA_SUPM, prctl PR_SET_TAGGED_ADDR_CTRL with PMLEN != 0), those two addresses differ: a user pointer whose top PMLEN bits hold a tag passes access_ok() after untagging, but the atomic is then performed on the still-tagged raw address. Supervisor-mode data accesses are not subject to the U-mode pointer masking (that is governed by menvcfg.PMM, which the kernel does not set), so hardware does not strip the tag for the kernel's own access. With Sv57 and PMLEN=16 the tag bits overlap the canonical-address bits, so a tagged pointer can name a canonical kernel virtual address (e.g. in the linear map) whose untagged form is a valid user address. An unprivileged process can thus make FUTEX_WAKE_OP perform an atomic read-modify-write on an arbitrary kernel address, with the matching FUTEX_OP_CMP_* result serving as a read oracle. get_user()/put_user()/raw_copy_{to,from}_user() already untag the pointer after the access_ok() check; do the same in the futex helpers so the atomic operates on the address that was actually validated. The Linux kernel CVE team has assigned CVE-2026-99016 to this issue. Affected and fixed versions =========================== Issue introduced in 6.13 with commit 2e1743085887ba3f553c2bb472a75a3ff744b242 and fixed in 6.18.57 with commit 2e5c80bbc062a8dda33e687ebf7be8f074ee4f7d Issue introduced in 6.13 with commit 2e1743085887ba3f553c2bb472a75a3ff744b242 and fixed in 7.2.11 with commit 8e48d8d51ab37b7decfbff3e2844e027a52ad6ea Issue introduced in 6.13 with commit 2e1743085887ba3f553c2bb472a75a3ff744b242 and fixed in 7.3 with commit 405290be962b32eec842776fbe3bdf81f15b1676 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-2026-99016 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/riscv/include/asm/futex.h 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/2e5c80bbc062a8dda33e687ebf7be8f074ee4f7d https://git.kernel.org/stable/c/8e48d8d51ab37b7decfbff3e2844e027a52ad6ea https://git.kernel.org/stable/c/405290be962b32eec842776fbe3bdf81f15b1676