On Wed, Feb 03, 2016 at 03:44:41AM +0000, Paul Burton wrote: > When an unsupported reloc is encountered in a module, we currently > blindly branch to whatever would be at its entry in the reloc handler > function pointer arrays. This may be NULL, or if the unsupported reloc > has a type greater than that of the supported reloc with the highest > type then we'll dereference some value after the function pointer array > & branch to that. The result is at best a kernel oops. > > Fix this by checking that the reloc type has an entry in the function > pointer array (ie. is less than the number of items in the array) and > that the handler is non-NULL, returning an error code to fail the module > load if no handler is found. > > Signed-off-by: Paul Burton <[email protected]> > Cc: James Hogan <[email protected]>
Reviewed-by: James Hogan <[email protected]> Cheers James > --- > > arch/mips/kernel/module-rela.c | 19 ++++++++++++++++--- > arch/mips/kernel/module.c | 19 ++++++++++++++++--- > 2 files changed, 32 insertions(+), 6 deletions(-) > > diff --git a/arch/mips/kernel/module-rela.c b/arch/mips/kernel/module-rela.c > index 2b70723..769e316 100644 > --- a/arch/mips/kernel/module-rela.c > +++ b/arch/mips/kernel/module-rela.c > @@ -109,9 +109,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char > *strtab, > struct module *me) > { > Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr; > + int (*handler)(struct module *me, u32 *location, Elf_Addr v); > Elf_Sym *sym; > u32 *location; > - unsigned int i; > + unsigned int i, type; > Elf_Addr v; > int res; > > @@ -134,9 +135,21 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char > *strtab, > return -ENOENT; > } > > - v = sym->st_value + rel[i].r_addend; > + type = ELF_MIPS_R_TYPE(rel[i]); > + > + if (type < ARRAY_SIZE(reloc_handlers_rela)) > + handler = reloc_handlers_rela[type]; > + else > + handler = NULL; > > - res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, > location, v); > + if (!handler) { > + pr_warn("%s: Unknown relocation type %u\n", > + me->name, type); > + return -EINVAL; > + } > + > + v = sym->st_value + rel[i].r_addend; > + res = handler(me, location, v); > if (res) > return res; > } > diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c > index 1833f51..2adf572 100644 > --- a/arch/mips/kernel/module.c > +++ b/arch/mips/kernel/module.c > @@ -197,9 +197,10 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, > struct module *me) > { > Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr; > + int (*handler)(struct module *me, u32 *location, Elf_Addr v); > Elf_Sym *sym; > u32 *location; > - unsigned int i; > + unsigned int i, type; > Elf_Addr v; > int res; > > @@ -223,9 +224,21 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, > return -ENOENT; > } > > - v = sym->st_value; > + type = ELF_MIPS_R_TYPE(rel[i]); > + > + if (type < ARRAY_SIZE(reloc_handlers_rel)) > + handler = reloc_handlers_rel[type]; > + else > + handler = NULL; > > - res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, > v); > + if (!handler) { > + pr_warn("%s: Unknown relocation type %u\n", > + me->name, type); > + return -EINVAL; > + } > + > + v = sym->st_value; > + res = handler(me, location, v); > if (res) > return res; > } > -- > 2.7.0 >
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