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Commit 5f71d977 authored by Sven Schnelle's avatar Sven Schnelle Committed by Helge Deller
Browse files

kexec_elf: remove parsing of section headers 



We're not using them, so we can drop the parsing.

Signed-off-by: default avatarSven Schnelle <svens@stackframe.org>
Reviewed-by: default avatarThiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent d34e0ad3

include/linux/kexec.h

+0 −1
Original line number Diff line number Diff line
@@ -226,7 +226,6 @@ struct kexec_elf_info { 


	const struct elfhdr *ehdr;

	const struct elf_phdr *proghdrs;

	struct elf_shdr *sechdrs;

};



int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,

kernel/kexec_elf.c

+0 −137
Original line number Diff line number Diff line
@@ -257,134 +257,6 @@ static int elf_read_phdrs(const char *buf, size_t len, 
	return 0;

}



/**

 * elf_is_shdr_sane - check that it is safe to use the section header

 * @buf_len:	size of the buffer in which the ELF file is loaded.

 */

static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)

{

	bool size_ok;



	/* SHT_NULL headers have undefined values, so we can't check them. */

	if (shdr->sh_type == SHT_NULL)

		return true;



	/* Now verify sh_entsize */

	switch (shdr->sh_type) {

	case SHT_SYMTAB:

		size_ok = shdr->sh_entsize == sizeof(Elf_Sym);

		break;

	case SHT_RELA:

		size_ok = shdr->sh_entsize == sizeof(Elf_Rela);

		break;

	case SHT_DYNAMIC:

		size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);

		break;

	case SHT_REL:

		size_ok = shdr->sh_entsize == sizeof(Elf_Rel);

		break;

	case SHT_NOTE:

	case SHT_PROGBITS:

	case SHT_HASH:

	case SHT_NOBITS:

	default:

		/*

		 * This is a section whose entsize requirements

		 * I don't care about.  If I don't know about

		 * the section I can't care about it's entsize

		 * requirements.

		 */

		size_ok = true;

		break;

	}



	if (!size_ok) {

		pr_debug("ELF section with wrong entry size.\n");

		return false;

	} else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {

		pr_debug("ELF section address wraps around.\n");

		return false;

	}



	if (shdr->sh_type != SHT_NOBITS) {

		if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {

			pr_debug("ELF section location wraps around.\n");

			return false;

		} else if (shdr->sh_offset + shdr->sh_size > buf_len) {

			pr_debug("ELF section not in file.\n");

			return false;

		}

	}



	return true;

}



static int elf_read_shdr(const char *buf, size_t len,

			 struct kexec_elf_info *elf_info,

			 int idx)

{

	struct elf_shdr *shdr = &elf_info->sechdrs[idx];

	const struct elfhdr *ehdr = elf_info->ehdr;

	const char *sbuf;

	struct elf_shdr *buf_shdr;



	sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);

	buf_shdr = (struct elf_shdr *) sbuf;



	shdr->sh_name      = elf32_to_cpu(ehdr, buf_shdr->sh_name);

	shdr->sh_type      = elf32_to_cpu(ehdr, buf_shdr->sh_type);

	shdr->sh_addr      = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);

	shdr->sh_offset    = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);

	shdr->sh_link      = elf32_to_cpu(ehdr, buf_shdr->sh_link);

	shdr->sh_info      = elf32_to_cpu(ehdr, buf_shdr->sh_info);



	/*

	 * The following fields have a type equivalent to Elf_Addr

	 * both in 32 bit and 64 bit ELF.

	 */

	shdr->sh_flags     = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);

	shdr->sh_size      = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);

	shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);

	shdr->sh_entsize   = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);



	return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;

}



/**

 * elf_read_shdrs - read the section headers from the buffer

 *

 * This function assumes that the section header table was checked for sanity.

 * Use elf_is_ehdr_sane() if it wasn't.

 */

static int elf_read_shdrs(const char *buf, size_t len,

			  struct kexec_elf_info *elf_info)

{

	size_t shdr_size, i;



	/*

	 * e_shnum is at most 65536 so calculating

	 * the size of the section header cannot overflow.

	 */

	shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;



	elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);

	if (!elf_info->sechdrs)

		return -ENOMEM;



	for (i = 0; i < elf_info->ehdr->e_shnum; i++) {

		int ret;



		ret = elf_read_shdr(buf, len, elf_info, i);

		if (ret) {

			kfree(elf_info->sechdrs);

			elf_info->sechdrs = NULL;

			return ret;

		}

	}



	return 0;

}



/**

 * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info

 * @buf:	Buffer to read ELF file from.
@@ -417,14 +289,6 @@ static int elf_read_from_buffer(const char *buf, size_t len, 
		if (ret)

			return ret;

	}

	if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {

		ret = elf_read_shdrs(buf, len, elf_info);

		if (ret) {

			kfree(elf_info->proghdrs);

			return ret;

		}

	}



	return 0;

}
@@ -434,7 +298,6 @@ static int elf_read_from_buffer(const char *buf, size_t len, 
void kexec_free_elf_info(struct kexec_elf_info *elf_info)

{

	kfree(elf_info->proghdrs);

	kfree(elf_info->sechdrs);

	memset(elf_info, 0, sizeof(*elf_info));

}

/**