From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Nicholas Piggin , Michael Ellerman , Sasha Levin Subject: [PATCH AUTOSEL 4.19 11/57] powerpc/64/module: REL32 relocation range check Date: Sun, 4 Nov 2018 08:50:58 -0500 Message-Id: <20181104135144.88324-11-sashal@kernel.org> In-Reply-To: <20181104135144.88324-1-sashal@kernel.org> References: <20181104135144.88324-1-sashal@kernel.org> List-ID: From: Nicholas Piggin [ Upstream commit b851ba02a6f3075f0f99c60c4bc30a4af80cf428 ] The recent module relocation overflow crash demonstrated that we have no range checking on REL32 relative relocations. This patch implements a basic check, the same kernel that previously oopsed and rebooted now continues with some of these errors when loading the module: module_64: x_tables: REL32 527703503449812 out of range! Possibly other relocations (ADDR32, REL16, TOC16, etc.) should also have overflow checks. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- arch/powerpc/kernel/module_64.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index b8d61e019d06..f7b1203bdaee 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -685,7 +685,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_PPC64_REL32: /* 32 bits relative (used by relative exception tables) */ - *(u32 *)location = value - (unsigned long)location; + /* Convert value to relative */ + value -= (unsigned long)location; + if (value + 0x80000000 > 0xffffffff) { + pr_err("%s: REL32 %li out of range!\n", + me->name, (long int)value); + return -ENOEXEC; + } + *(u32 *)location = value; break; case R_PPC64_TOCSAVE: -- 2.17.1