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scripts/kallsyms: fix offset overflow of kallsyms_relative_base 

Since commit 5e5c4fa787 ("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: 5e5c4fa787 ("scripts/kallsyms: shrink table before sorting it")
Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Masahiro Yamada 2019-12-09 12:51:48 +09:00
parent c8f3dea90e
commit fd2ab2f661
1 changed files with 18 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
scripts/kallsyms.c
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@ -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");
}