[PATCH 4.19 002/205] powerpc/64/module: REL32 relocation range check
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2018-11-19 16:31:00
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4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Piggin <npiggin@gmail.com> [ 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 <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/powerpc/kernel/module_64.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c@@ -680,7 +680,14 @@ int apply_relocate_add(Elf64_Shdr *sechd 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: