kallsyms: increase maximum kernel symbol length to 512

Rust symbols can become quite long due to namespacing introduced by modules, types, traits, generics, etc. For instance, the following code: pub mod my_module { pub struct MyType; pub struct MyGenericType<T>(T); pub trait MyTrait { fn my_method() -> u32; } impl MyTrait for MyGenericType<MyType> { fn my_method() -> u32 { 42 } } } generates a symbol of length 96 when using the upcoming v0 mangling scheme: _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method At the moment, Rust symbols may reach up to 300 in length. Setting 512 as the maximum seems like a reasonable choice to keep some headroom. Reviewed-by: Kees Cook <[email protected]> Reviewed-by: Petr Mladek <[email protected]> Reviewed-by: Greg Kroah-Hartman <[email protected]> Co-developed-by: Alex Gaynor <[email protected]> Signed-off-by: Alex Gaynor <[email protected]> Co-developed-by: Wedson Almeida Filho <[email protected]> Signed-off-by: Wedson Almeida Filho <[email protected]> Co-developed-by: Gary Guo <[email protected]> Signed-off-by: Gary Guo <[email protected]> Co-developed-by: Boqun Feng <[email protected]> Signed-off-by: Boqun Feng <[email protected]> Signed-off-by: Miguel Ojeda <[email protected]>
Fraxoor · Sep 28, 2022 · b8a94bf · b8a94bf
1 parent 73bbb94
commit b8a94bf
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Showing 6 changed files with 8 additions and 8 deletions.
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
@@ -15,7 +15,7 @@
 
 #include <asm/sections.h>
 
-#define KSYM_NAME_LEN 128
+#define KSYM_NAME_LEN 512
 #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s %s]") + \
 			(KSYM_NAME_LEN - 1) + \
 			2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + \

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
@@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
 	 * we use the smallest/strictest upper bound possible (56, based on
 	 * the current definition of MODULE_NAME_LEN) to prevent overflows.
 	 */
-	BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
+	BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512);
 
 	relas = (Elf_Rela *) relasec->sh_addr;
 	/* For each rela in this klp relocation section */
@@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
 
 		/* Format: .klp.sym.sym_objname.sym_name,sympos */
 		cnt = sscanf(strtab + sym->st_name,
-			     ".klp.sym.%55[^.].%127[^,],%lu",
+			     ".klp.sym.%55[^.].%511[^,],%lu",
 			     sym_objname, sym_name, &sympos);
 		if (cnt != 3) {
 			pr_err("symbol %s has an incorrectly formatted name\n",

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
@@ -30,7 +30,7 @@
 #define _stringify_1(x)	#x
 #define _stringify(x)	_stringify_1(x)
 
-#define KSYM_NAME_LEN		128
+#define KSYM_NAME_LEN		512
 
 /*
  * A substantially bigger size than the current maximum.
@@ -39,7 +39,7 @@
  * for the fscanf() format string. Therefore, a _Static_assert() is
  * used instead to maintain the relationship with KSYM_NAME_LEN.
  */
-#define KSYM_NAME_LEN_BUFFER	512
+#define KSYM_NAME_LEN_BUFFER	2048
 _Static_assert(
 	KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
 	"Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"

diff --git a/tools/include/linux/kallsyms.h b/tools/include/linux/kallsyms.h
@@ -6,7 +6,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#define KSYM_NAME_LEN 128
+#define KSYM_NAME_LEN 512
 
 struct module;
 

diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
@@ -97,7 +97,7 @@ struct perf_record_throttle {
 };
 
 #ifndef KSYM_NAME_LEN
-#define KSYM_NAME_LEN 256
+#define KSYM_NAME_LEN 512
 #endif
 
 struct perf_record_ksymbol {

diff --git a/tools/lib/symbol/kallsyms.h b/tools/lib/symbol/kallsyms.h
@@ -7,7 +7,7 @@
 #include <linux/types.h>
 
 #ifndef KSYM_NAME_LEN
-#define KSYM_NAME_LEN 256
+#define KSYM_NAME_LEN 512
 #endif
 
 static inline u8 kallsyms2elf_binding(char type)