| Message ID | 20181023221535.4740-1-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | modpost: validate symbol names also in find_elf_symbol | expand |
On Wed, Oct 24, 2018 at 7:15 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > 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:$x.0 > > This change adds a call to is_valid_name to find_elf_symbol, similarly > to how it's already used in find_elf_symbol2. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- Applied to linux-kbuild. Thanks! > scripts/mod/modpost.c | 50 ++++++++++++++++++++++--------------------- > 1 file changed, 26 insertions(+), 24 deletions(-) > > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index 0d998c54564d..b709b2e623d6 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -1204,6 +1204,30 @@ static int secref_whitelist(const struct sectioncheck *mismatch, > return 1; > } > > +static inline int is_arm_mapping_symbol(const char *str) > +{ > + return str[0] == '$' && 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] == '$' && strchr("axtd", str[1]) > - && (str[2] == '\0' || str[2] == '.'); > -} > - > -/* > - * If there's no name there, ignore it; likewise, ignore it if it's > - * one of the magic symbols emitted used by current ARM tools. > - * > - * Otherwise if find_symbols_between() returns those symbols, they'll > - * fail the whitelist tests and cause lots of false alarms ... fixable > - * only by merging __exit and __init sections into __text, bloating > - * the kernel (which is especially evil on embedded platforms). > - */ > -static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) > -{ > - const char *name = elf->strtab + sym->st_name; > - > - if (!name || !strlen(name)) > - return 0; > - return !is_arm_mapping_symbol(name); > -} > - > /* > * Find symbols before or equal addr and after addr - in the section sec. > * If we find two symbols with equal offset prefer one with a valid name. > -- > 2.19.1.568.g152ad8e336-goog >
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 0d998c54564d..b709b2e623d6 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1204,6 +1204,30 @@ static int secref_whitelist(const struct sectioncheck *mismatch, return 1; } +static inline int is_arm_mapping_symbol(const char *str) +{ + return str[0] == '$' && 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] == '$' && strchr("axtd", str[1]) - && (str[2] == '\0' || str[2] == '.'); -} - -/* - * If there's no name there, ignore it; likewise, ignore it if it's - * one of the magic symbols emitted used by current ARM tools. - * - * Otherwise if find_symbols_between() returns those symbols, they'll - * fail the whitelist tests and cause lots of false alarms ... fixable - * only by merging __exit and __init sections into __text, bloating - * the kernel (which is especially evil on embedded platforms). - */ -static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) -{ - const char *name = elf->strtab + sym->st_name; - - if (!name || !strlen(name)) - return 0; - return !is_arm_mapping_symbol(name); -} - /* * Find symbols before or equal addr and after addr - in the section sec. * If we find two symbols with equal offset prefer one with a valid name.
If an ARM mapping symbol shares an address with a valid symbol, find_elf_symbol can currently return the mapping symbol instead, as the symbol is not validated. This can result in confusing warnings: WARNING: vmlinux.o(.text+0x18f4028): Section mismatch in reference from the function set_reset_devices() to the variable .init.text:$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: Sami Tolvanen <samitolvanen@google.com> --- scripts/mod/modpost.c | 50 ++++++++++++++++++++++--------------------- 1 file changed, 26 insertions(+), 24 deletions(-)