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 0633C22AE7F; Mon, 31 Mar 2025 14:37:08 +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=1743431829; cv=none; b=Q5DPg3pMu47c/l0KGvvGH/BhFfo280+zP/VgvtSEZ0j0yeWXV9RJ7QzTNmZrk20EjpB+d5hu+t5lklfgisoZETR8z2ScYoOxdC2eb0Teg7ynNyNnAwQndhSCg5HSA1ER56Ij6HT1rujHVw6cvT9QJWzRARrd7Usu3rDZnEXU5u0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743431829; c=relaxed/simple; bh=5ADO/3ZB6u14eIhTvT/hIqhq1OHtuLq3qs53bMniVfQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=KpxPPIQOoF4sMz0//BPaQg+MJHuBMDeRAqYYszRn0J63Sxj0uElb/K6+X1BNB/ygPkA6RFX/I6KirYpNhGmmG5M6YyN6r2A+NHvsHS8xtyJHu3Pgnvb+vbe27SJZIg6+EzE8uFGtwb5lkK9G6goVfHNSuBmOdzCjdrYU9QWD9nc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hN6I1sv2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hN6I1sv2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEAFCC4CEE3; Mon, 31 Mar 2025 14:37:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743431828; bh=5ADO/3ZB6u14eIhTvT/hIqhq1OHtuLq3qs53bMniVfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hN6I1sv2sf3qbhbXLBXmFQmxmUs+cak2QM4XBFFGfUuvJpvmCP2OujuzeCSTSm4Bo WzD60mqzv0whzjU3LoTz0h7LpNBgJ9D0cf+/SOYM550ecZyra8yPk8z+eaFYpyHfdB FMoMuNnaIh8mIOmiURv8dHXlXgQTe0pi86vZYXTkGxhaFyhh7xHGxaJv0Ec2q3sv73 F21PArnZuq9zY5MNhRKMjkw00sHuVM8tfVpXSh6ckNlZaIop+EF9Qrcbexe9yXj1ib g5yz+738adX6muceP6hL7nChKNm+5LJ4XkuRQuaATsweZnd2wwZhE/HtpZl0U5u3j9 13OGZzbkuWoBg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Kirill A. Shutemov" , Ingo Molnar , Kai Huang , Tom Lendacky , Andy Lutomirski , Linus Torvalds , Sasha Levin , dave.hansen@linux.intel.com, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org Subject: [PATCH AUTOSEL 5.15 6/6] x86/mm/ident_map: Fix theoretical virtual address overflow to zero Date: Mon, 31 Mar 2025 10:36:51 -0400 Message-Id: <20250331143652.1686503-6-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250331143652.1686503-1-sashal@kernel.org> References: <20250331143652.1686503-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.179 Content-Transfer-Encoding: 8bit From: "Kirill A. Shutemov" [ Upstream commit f666c92090a41ac5524dade63ff96b3adcf8c2ab ] The current calculation of the 'next' virtual address in the page table initialization functions in arch/x86/mm/ident_map.c doesn't protect against wrapping to zero. This is a theoretical issue that cannot happen currently, the problematic case is possible only if the user sets a high enough x86_mapping_info::offset value - which no current code in the upstream kernel does. ( The wrapping to zero only occurs if the top PGD entry is accessed. There are no such users upstream. Only hibernate_64.c uses x86_mapping_info::offset, and it operates on the direct mapping range, which is not the top PGD entry. ) Should such an overflow happen, it can result in page table corruption and a hang. To future-proof this code, replace the manual 'next' calculation with p?d_addr_end() which handles wrapping correctly. [ Backporter's note: there's no need to backport this patch. ] Signed-off-by: Kirill A. Shutemov Signed-off-by: Ingo Molnar Reviewed-by: Kai Huang Reviewed-by: Tom Lendacky Cc: Andy Lutomirski Cc: Linus Torvalds Link: https://lore.kernel.org/r/20241016111458.846228-2-kirill.shutemov@linux.intel.com Signed-off-by: Sasha Levin --- arch/x86/mm/ident_map.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c index 968d7005f4a72..2f383e288c430 100644 --- a/arch/x86/mm/ident_map.c +++ b/arch/x86/mm/ident_map.c @@ -27,9 +27,7 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, pud_t *pud = pud_page + pud_index(addr); pmd_t *pmd; - next = (addr & PUD_MASK) + PUD_SIZE; - if (next > end) - next = end; + next = pud_addr_end(addr, end); if (info->direct_gbpages) { pud_t pudval; @@ -68,10 +66,7 @@ static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page, p4d_t *p4d = p4d_page + p4d_index(addr); pud_t *pud; - next = (addr & P4D_MASK) + P4D_SIZE; - if (next > end) - next = end; - + next = p4d_addr_end(addr, end); if (p4d_present(*p4d)) { pud = pud_offset(p4d, 0); result = ident_pud_init(info, pud, addr, next); @@ -113,10 +108,7 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, pgd_t *pgd = pgd_page + pgd_index(addr); p4d_t *p4d; - next = (addr & PGDIR_MASK) + PGDIR_SIZE; - if (next > end) - next = end; - + next = pgd_addr_end(addr, end); if (pgd_present(*pgd)) { p4d = p4d_offset(pgd, 0); result = ident_p4d_init(info, p4d, addr, next); -- 2.39.5