| Message ID | 20191209035148.17048-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | scripts/kallsyms: fix offset overflow of kallsyms_relative_base | expand |
On Mon, Dec 9, 2019 at 12:52 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > Since commit 5e5c4fa78745 ("scripts/kallsyms: shrink table before > sorting it"), kallsyms_relative_base can be larger than _text, which > causes overflow when building the 32-bit kernel. > > https://lkml.org/lkml/2019/12/7/156 > > This is because _text is, unless --all-symbols is specified, now > trimmed from the symbol table before record_relative_base() is called. > > Handle the offset signedness also for kallsyms_relative_base. Introduce > a new helper, output_address(), to reduce the code duplication. > > Fixes: 5e5c4fa78745 ("scripts/kallsyms: shrink table before sorting it") > Reported-by: Olof Johansson <olof@lixom.net> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > Applied to linux-kbuid. > scripts/kallsyms.c | 38 ++++++++++++++++++-------------------- > 1 file changed, 18 insertions(+), 20 deletions(-) > > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c > index fb55f262f42d..94153732ec00 100644 > --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -310,6 +310,15 @@ static void output_label(const char *label) > printf("%s:\n", label); > } > > +/* Provide proper symbols relocatability by their '_text' relativeness. */ > +static void output_address(unsigned long long addr) > +{ > + if (_text <= addr) > + printf("\tPTR\t_text + %#llx\n", addr - _text); > + else > + printf("\tPTR\t_text - %#llx\n", _text - addr); > +} > + > /* uncompress a compressed symbol. When this function is called, the best table > * might still be compressed itself, so the function needs to be recursive */ > static int expand_symbol(const unsigned char *data, int len, char *result) > @@ -360,19 +369,6 @@ static void write_src(void) > > printf("\t.section .rodata, \"a\"\n"); > > - /* Provide proper symbols relocatability by their relativeness > - * to a fixed anchor point in the runtime image, either '_text' > - * for absolute address tables, in which case the linker will > - * emit the final addresses at build time. Otherwise, use the > - * offset relative to the lowest value encountered of all relative > - * symbols, and emit non-relocatable fixed offsets that will be fixed > - * up at runtime. > - * > - * The symbol names cannot be used to construct normal symbol > - * references as the list of symbols contains symbols that are > - * declared static and are private to their .o files. This prevents > - * .tmp_kallsyms.o or any other object from referencing them. > - */ > if (!base_relative) > output_label("kallsyms_addresses"); > else > @@ -380,6 +376,13 @@ static void write_src(void) > > for (i = 0; i < table_cnt; i++) { > if (base_relative) { > + /* > + * Use the offset relative to the lowest value > + * encountered of all relative symbols, and emit > + * non-relocatable fixed offsets that will be fixed > + * up at runtime. > + */ > + > long long offset; > int overflow; > > @@ -402,12 +405,7 @@ static void write_src(void) > } > printf("\t.long\t%#x\n", (int)offset); > } else if (!symbol_absolute(&table[i])) { > - if (_text <= table[i].addr) > - printf("\tPTR\t_text + %#llx\n", > - table[i].addr - _text); > - else > - printf("\tPTR\t_text - %#llx\n", > - _text - table[i].addr); > + output_address(table[i].addr); > } else { > printf("\tPTR\t%#llx\n", table[i].addr); > } > @@ -416,7 +414,7 @@ static void write_src(void) > > if (base_relative) { > output_label("kallsyms_relative_base"); > - printf("\tPTR\t_text - %#llx\n", _text - relative_base); > + output_address(relative_base); > printf("\n"); > } > > -- > 2.17.1 >
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index fb55f262f42d..94153732ec00 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -310,6 +310,15 @@ static void output_label(const char *label) printf("%s:\n", label); } +/* Provide proper symbols relocatability by their '_text' relativeness. */ +static void output_address(unsigned long long addr) +{ + if (_text <= addr) + printf("\tPTR\t_text + %#llx\n", addr - _text); + else + printf("\tPTR\t_text - %#llx\n", _text - addr); +} + /* uncompress a compressed symbol. When this function is called, the best table * might still be compressed itself, so the function needs to be recursive */ static int expand_symbol(const unsigned char *data, int len, char *result) @@ -360,19 +369,6 @@ static void write_src(void) printf("\t.section .rodata, \"a\"\n"); - /* Provide proper symbols relocatability by their relativeness - * to a fixed anchor point in the runtime image, either '_text' - * for absolute address tables, in which case the linker will - * emit the final addresses at build time. Otherwise, use the - * offset relative to the lowest value encountered of all relative - * symbols, and emit non-relocatable fixed offsets that will be fixed - * up at runtime. - * - * The symbol names cannot be used to construct normal symbol - * references as the list of symbols contains symbols that are - * declared static and are private to their .o files. This prevents - * .tmp_kallsyms.o or any other object from referencing them. - */ if (!base_relative) output_label("kallsyms_addresses"); else @@ -380,6 +376,13 @@ static void write_src(void) for (i = 0; i < table_cnt; i++) { if (base_relative) { + /* + * Use the offset relative to the lowest value + * encountered of all relative symbols, and emit + * non-relocatable fixed offsets that will be fixed + * up at runtime. + */ + long long offset; int overflow; @@ -402,12 +405,7 @@ static void write_src(void) } printf("\t.long\t%#x\n", (int)offset); } else if (!symbol_absolute(&table[i])) { - if (_text <= table[i].addr) - printf("\tPTR\t_text + %#llx\n", - table[i].addr - _text); - else - printf("\tPTR\t_text - %#llx\n", - _text - table[i].addr); + output_address(table[i].addr); } else { printf("\tPTR\t%#llx\n", table[i].addr); } @@ -416,7 +414,7 @@ static void write_src(void) if (base_relative) { output_label("kallsyms_relative_base"); - printf("\tPTR\t_text - %#llx\n", _text - relative_base); + output_address(relative_base); printf("\n"); }
Since commit 5e5c4fa78745 ("scripts/kallsyms: shrink table before sorting it"), kallsyms_relative_base can be larger than _text, which causes overflow when building the 32-bit kernel. https://lkml.org/lkml/2019/12/7/156 This is because _text is, unless --all-symbols is specified, now trimmed from the symbol table before record_relative_base() is called. Handle the offset signedness also for kallsyms_relative_base. Introduce a new helper, output_address(), to reduce the code duplication. Fixes: 5e5c4fa78745 ("scripts/kallsyms: shrink table before sorting it") Reported-by: Olof Johansson <olof@lixom.net> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- scripts/kallsyms.c | 38 ++++++++++++++++++-------------------- 1 file changed, 18 insertions(+), 20 deletions(-)