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Commit b851ba02 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/64/module: REL32 relocation range check 



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: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent dd76ff5a

arch/powerpc/kernel/module_64.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -680,7 +680,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, 




		case R_PPC64_REL32:

		case R_PPC64_REL32:

			/* 32 bits relative (used by relative exception tables) */

			/* 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;

			break;





		case R_PPC64_TOCSAVE:

		case R_PPC64_TOCSAVE: