From: Shuah Khan skhan@linuxfoundation.org
[ Upstream commit 7fd982f394c42f25a73fe9dfbf1e6b11fa26b40a ]
elf_validity_check() checks ELF headers for errors and ELF Spec. compliance and if any of them fail it returns -ENOEXEC from all of these error paths. Almost all of them don't print any messages.
When elf_validity_check() returns an error, load_module() prints an error message without error code. It is hard to determine why the module ELF structure is invalid, even if load_module() prints the error code which is -ENOEXEC in all of these cases.
Change to print useful error messages from elf_validity_check() to clearly say what went wrong and why the ELF validity checks failed.
Remove the load_module() error message which is no longer needed. This patch includes changes to fix build warns on 32-bit platforms:
warning: format '%llu' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Off' {aka 'unsigned int'} Reported-by: kernel test robot lkp@intel.com
Signed-off-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/module.c | 75 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 54 insertions(+), 21 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c index 83991c2d5af9..256b3c80a771 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2967,14 +2967,29 @@ static int elf_validity_check(struct load_info *info) Elf_Shdr *shdr, *strhdr; int err;
- if (info->len < sizeof(*(info->hdr))) - return -ENOEXEC; + if (info->len < sizeof(*(info->hdr))) { + pr_err("Invalid ELF header len %lu\n", info->len); + goto no_exec; + }
- if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0 - || info->hdr->e_type != ET_REL - || !elf_check_arch(info->hdr) - || info->hdr->e_shentsize != sizeof(Elf_Shdr)) - return -ENOEXEC; + if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) { + pr_err("Invalid ELF header magic: != %s\n", ELFMAG); + goto no_exec; + } + if (info->hdr->e_type != ET_REL) { + pr_err("Invalid ELF header type: %u != %u\n", + info->hdr->e_type, ET_REL); + goto no_exec; + } + if (!elf_check_arch(info->hdr)) { + pr_err("Invalid architecture in ELF header: %u\n", + info->hdr->e_machine); + goto no_exec; + } + if (info->hdr->e_shentsize != sizeof(Elf_Shdr)) { + pr_err("Invalid ELF section header size\n"); + goto no_exec; + }
/* * e_shnum is 16 bits, and sizeof(Elf_Shdr) is @@ -2983,8 +2998,10 @@ static int elf_validity_check(struct load_info *info) */ if (info->hdr->e_shoff >= info->len || (info->hdr->e_shnum * sizeof(Elf_Shdr) > - info->len - info->hdr->e_shoff)) - return -ENOEXEC; + info->len - info->hdr->e_shoff)) { + pr_err("Invalid ELF section header overflow\n"); + goto no_exec; + }
info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;
@@ -2992,13 +3009,19 @@ static int elf_validity_check(struct load_info *info) * Verify if the section name table index is valid. */ if (info->hdr->e_shstrndx == SHN_UNDEF - || info->hdr->e_shstrndx >= info->hdr->e_shnum) - return -ENOEXEC; + || info->hdr->e_shstrndx >= info->hdr->e_shnum) { + pr_err("Invalid ELF section name index: %d || e_shstrndx (%d) >= e_shnum (%d)\n", + info->hdr->e_shstrndx, info->hdr->e_shstrndx, + info->hdr->e_shnum); + goto no_exec; + }
strhdr = &info->sechdrs[info->hdr->e_shstrndx]; err = validate_section_offset(info, strhdr); - if (err < 0) + if (err < 0) { + pr_err("Invalid ELF section hdr(type %u)\n", strhdr->sh_type); return err; + }
/* * The section name table must be NUL-terminated, as required @@ -3006,8 +3029,10 @@ static int elf_validity_check(struct load_info *info) * strings in the section safe. */ info->secstrings = (void *)info->hdr + strhdr->sh_offset; - if (info->secstrings[strhdr->sh_size - 1] != '\0') - return -ENOEXEC; + if (info->secstrings[strhdr->sh_size - 1] != '\0') { + pr_err("ELF Spec violation: section name table isn't null terminated\n"); + goto no_exec; + }
/* * The code assumes that section 0 has a length of zero and @@ -3015,8 +3040,11 @@ static int elf_validity_check(struct load_info *info) */ if (info->sechdrs[0].sh_type != SHT_NULL || info->sechdrs[0].sh_size != 0 - || info->sechdrs[0].sh_addr != 0) - return -ENOEXEC; + || info->sechdrs[0].sh_addr != 0) { + pr_err("ELF Spec violation: section 0 type(%d)!=SH_NULL or non-zero len or addr\n", + info->sechdrs[0].sh_type); + goto no_exec; + }
for (i = 1; i < info->hdr->e_shnum; i++) { shdr = &info->sechdrs[i]; @@ -3026,8 +3054,12 @@ static int elf_validity_check(struct load_info *info) continue; case SHT_SYMTAB: if (shdr->sh_link == SHN_UNDEF - || shdr->sh_link >= info->hdr->e_shnum) - return -ENOEXEC; + || shdr->sh_link >= info->hdr->e_shnum) { + pr_err("Invalid ELF sh_link!=SHN_UNDEF(%d) or (sh_link(%d) >= hdr->e_shnum(%d)\n", + shdr->sh_link, shdr->sh_link, + info->hdr->e_shnum); + goto no_exec; + } fallthrough; default: err = validate_section_offset(info, shdr); @@ -3049,6 +3081,9 @@ static int elf_validity_check(struct load_info *info) }
return 0; + +no_exec: + return -ENOEXEC; }
#define COPY_CHUNK_SIZE (16*PAGE_SIZE) @@ -3925,10 +3960,8 @@ static int load_module(struct load_info *info, const char __user *uargs, * sections. */ err = elf_validity_check(info); - if (err) { - pr_err("Module has invalid ELF structures\n"); + if (err) goto free_copy; - }
/* * Everything checks out, so set up the section info