From: Mark Rutland mark.rutland@arm.com
mainline inclusion from mainline-v5.5-rc1 commit bd8b21d3dd661658addc1cd4cc869bab11d28596 category: bugfix bugzilla: 25285 CVE: NA
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When we load a module, we have to perform some special work for a couple of named sections. To do this, we iterate over all of the module's sections, and perform work for each section we recognize.
To make it easier to handle the unexpected absence of a section, and to make the section-specific logic easer to read, let's factor the section search into a helper. Similar is already done in the core module loader, and other architectures (and ideally we'd unify these in future).
If we expect a module to have an ftrace trampoline section, but it doesn't have one, we'll now reject loading the module. When ARM64_MODULE_PLTS is selected, any correctly built module should have one (and this is assumed by arm64's ftrace PLT code) and the absence of such a section implies something has gone wrong at build time.
Subsequent patches will make use of the new helper.
Signed-off-by: Mark Rutland mark.rutland@arm.com Reviewed-by: Ard Biesheuvel ard.biesheuvel@linaro.org Reviewed-by: Torsten Duwe duwe@suse.de Tested-by: Amit Daniel Kachhap amit.kachhap@arm.com Tested-by: Torsten Duwe duwe@suse.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: James Morse james.morse@arm.com Cc: Will Deacon will@kernel.org Signed-off-by: Pu Lehui pulehui@huawei.com Reviewed-by: Jian Cheng cj.chengjian@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- arch/arm64/kernel/module.c | 35 ++++++++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index 834ecf108b53..55b00bfb704f 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -484,22 +484,39 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, return -ENOEXEC; }
-int module_finalize(const Elf_Ehdr *hdr, - const Elf_Shdr *sechdrs, - struct module *me) +static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, + const Elf_Shdr *sechdrs, + const char *name) { const Elf_Shdr *s, *se; const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { - if (strcmp(".altinstructions", secstrs + s->sh_name) == 0) - apply_alternatives_module((void *)s->sh_addr, s->sh_size); + if (strcmp(name, secstrs + s->sh_name) == 0) + return s; + } + + return NULL; +} + +int module_finalize(const Elf_Ehdr *hdr, + const Elf_Shdr *sechdrs, + struct module *me) +{ + const Elf_Shdr *s; + + s = find_section(hdr, sechdrs, ".altinstructions"); + if (s) + apply_alternatives_module((void *)s->sh_addr, s->sh_size); + #ifdef CONFIG_ARM64_MODULE_PLTS - if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && - !strcmp(".text.ftrace_trampoline", secstrs + s->sh_name)) - me->arch.ftrace_trampoline = (void *)s->sh_addr; -#endif + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE)) { + s = find_section(hdr, sechdrs, ".text.ftrace_trampoline"); + if (!s) + return -ENOEXEC; + me->arch.ftrace_trampoline = (void *)s->sh_addr; } +#endif
return 0; }