hulk inclusion category: feature bugzilla: 51921 CVE: NA
---------------------------
We are planning to add livepatch without ftrace support for arm in the next commit. However after commit 425595a7fc20 ("livepatch: reuse module loader code to write relocations") merged, the klp relocations is done by apply_relocate function.
The mod->arch.{core,init}.plt pointers were problematic for livepatch because they pointed within temporary section headers (provided by the module loader via info->sechdrs) that would be freed after module load.
Here we take same modification based on commit c8ebf64eab74 ("arm64/module: use plt section indices for relocations") to solve.
Signed-off-by: Dong Kai dongkai11@huawei.com Signed-off-by: Ye Weihua yeweihua4@huawei.com Signed-off-by: Zheng Yejian zhengyejian1@huawei.com --- arch/arm/include/asm/module.h | 4 +++- arch/arm/kernel/ftrace.c | 4 ++-- arch/arm/kernel/module-plts.c | 22 ++++++++++++++-------- arch/arm/kernel/module.c | 4 ++-- 4 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h index 07c51a34f77d..761305646831 100644 --- a/arch/arm/include/asm/module.h +++ b/arch/arm/include/asm/module.h @@ -21,6 +21,7 @@ struct plt_entries { struct mod_plt_sec { struct elf32_shdr *plt; struct plt_entries *plt_ent; + int plt_shndx; int plt_count; };
@@ -36,7 +37,8 @@ struct mod_arch_specific { };
struct module; -u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val); +u32 get_module_plt(struct module *mod, Elf32_Shdr *sechdrs, + unsigned long loc, Elf32_Addr val); #ifdef CONFIG_ARM_MODULE_PLTS bool in_module_plt(unsigned long loc); #else diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index a0b6d1e3812f..d99874cc9b2e 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -158,7 +158,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) new = ftrace_call_replace(ip, aaddr, !mod); #ifdef CONFIG_ARM_MODULE_PLTS if (!new && mod) { - aaddr = get_module_plt(mod, ip, aaddr); + aaddr = get_module_plt(mod, NULL, ip, aaddr); new = ftrace_call_replace(ip, aaddr, true); } #endif @@ -204,7 +204,7 @@ int ftrace_make_nop(struct module *mod, !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); #ifdef CONFIG_ARM_MODULE_PLTS if (!old && mod) { - aaddr = get_module_plt(mod, ip, aaddr); + aaddr = get_module_plt(mod, NULL, ip, aaddr); old = ftrace_call_replace(ip, aaddr, true); } #endif diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index da2ee8d6ef1a..630388dbbf25 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -43,16 +43,19 @@ static void prealloc_fixed(struct mod_plt_sec *pltsec, struct plt_entries *plt) memcpy(plt->lit, fixed_plts, sizeof(fixed_plts)); }
-u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val) +u32 get_module_plt(struct module *mod, Elf32_Shdr *sechdrs, + unsigned long loc, Elf32_Addr val) { struct mod_plt_sec *pltsec = !within_module_init(loc, mod) ? &mod->arch.core : &mod->arch.init; + Elf32_Shdr *plt_shdr = sechdrs ? &sechdrs[pltsec->plt_shndx] : + pltsec->plt; struct plt_entries *plt; int idx;
/* cache the address, ELF header is available only during module load */ if (!pltsec->plt_ent) - pltsec->plt_ent = (struct plt_entries *)pltsec->plt->sh_addr; + pltsec->plt_ent = (struct plt_entries *)plt_shdr->sh_addr; plt = pltsec->plt_ent;
prealloc_fixed(pltsec, plt); @@ -80,7 +83,7 @@ u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val) }
pltsec->plt_count++; - BUG_ON(pltsec->plt_count * PLT_ENT_SIZE > pltsec->plt->sh_size); + BUG_ON(pltsec->plt_count * PLT_ENT_SIZE > plt_shdr->sh_size);
if (!idx) /* Populate a new set of entries */ @@ -213,21 +216,24 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, unsigned long init_plts = ARRAY_SIZE(fixed_plts); Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum; Elf32_Sym *syms = NULL; + int i = 0;
/* * To store the PLTs, we expand the .text section for core module code * and for initialization code. */ - for (s = sechdrs; s < sechdrs_end; ++s) { - if (strcmp(".plt", secstrings + s->sh_name) == 0) + for (s = sechdrs; s < sechdrs_end; ++s, ++i) { + if (strcmp(".plt", secstrings + s->sh_name) == 0) { mod->arch.core.plt = s; - else if (strcmp(".init.plt", secstrings + s->sh_name) == 0) + mod->arch.core.plt_shndx = i; + } else if (strcmp(".init.plt", secstrings + s->sh_name) == 0) { mod->arch.init.plt = s; - else if (s->sh_type == SHT_SYMTAB) + mod->arch.init.plt_shndx = i; + } else if (s->sh_type == SHT_SYMTAB) syms = (Elf32_Sym *)s->sh_addr; }
- if (!mod->arch.core.plt || !mod->arch.init.plt) { + if (!mod->arch.core.plt_shndx || !mod->arch.init.plt_shndx) { pr_err("%s: module PLT section(s) missing\n", mod->name); return -ENOEXEC; } diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c index e74d84f58b77..6c310d49f71c 100644 --- a/arch/arm/kernel/module.c +++ b/arch/arm/kernel/module.c @@ -182,7 +182,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) && (offset <= (s32)0xfe000000 || offset >= (s32)0x02000000)) - offset = get_module_plt(module, loc, + offset = get_module_plt(module, sechdrs, loc, offset + loc + 8) - loc - 8;
@@ -353,7 +353,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) && (offset <= (s32)0xff000000 || offset >= (s32)0x01000000)) - offset = get_module_plt(module, loc, + offset = get_module_plt(module, sechdrs, loc, offset + loc + 4) - loc - 4;