Commit 5818c683 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Masahiro Yamada
Browse files

modpost: validate symbol names also in find_elf_symbol 



If an ARM mapping symbol shares an address with a valid symbol,
find_elf_symbol can currently return the mapping symbol instead, as the
symbol is not validated. This can result in confusing warnings:

  WARNING: vmlinux.o(.text+0x18f4028): Section mismatch in reference
  from the function set_reset_devices() to the variable .init.text:$x.0

This change adds a call to is_valid_name to find_elf_symbol, similarly
to how it's already used in find_elf_symbol2.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
parent 813af51f

scripts/mod/modpost.c

+26 −24
Original line number Diff line number Diff line
@@ -1204,6 +1204,30 @@ static int secref_whitelist(const struct sectioncheck *mismatch, 
	return 1;

}



static inline int is_arm_mapping_symbol(const char *str)

{

	return str[0] == '$' && strchr("axtd", str[1])

	       && (str[2] == '\0' || str[2] == '.');

}



/*

 * If there's no name there, ignore it; likewise, ignore it if it's

 * one of the magic symbols emitted used by current ARM tools.

 *

 * Otherwise if find_symbols_between() returns those symbols, they'll

 * fail the whitelist tests and cause lots of false alarms ... fixable

 * only by merging __exit and __init sections into __text, bloating

 * the kernel (which is especially evil on embedded platforms).

 */

static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)

{

	const char *name = elf->strtab + sym->st_name;



	if (!name || !strlen(name))

		return 0;

	return !is_arm_mapping_symbol(name);

}



/**

 * Find symbol based on relocation record info.

 * In some cases the symbol supplied is a valid symbol so
@@ -1229,6 +1253,8 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr, 
			continue;

		if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)

			continue;

		if (!is_valid_name(elf, sym))

			continue;

		if (sym->st_value == addr)

			return sym;

		/* Find a symbol nearby - addr are maybe negative */
@@ -1247,30 +1273,6 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr, 
		return NULL;

}



static inline int is_arm_mapping_symbol(const char *str)

{

	return str[0] == '$' && strchr("axtd", str[1])

	       && (str[2] == '\0' || str[2] == '.');

}



/*

 * If there's no name there, ignore it; likewise, ignore it if it's

 * one of the magic symbols emitted used by current ARM tools.

 *

 * Otherwise if find_symbols_between() returns those symbols, they'll

 * fail the whitelist tests and cause lots of false alarms ... fixable

 * only by merging __exit and __init sections into __text, bloating

 * the kernel (which is especially evil on embedded platforms).

 */

static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)

{

	const char *name = elf->strtab + sym->st_name;



	if (!name || !strlen(name))

		return 0;

	return !is_arm_mapping_symbol(name);

}



/*

 * Find symbols before or equal addr and after addr - in the section sec.

 * If we find two symbols with equal offset prefer one with a valid name.

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