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Subject[PATCH v7 01/25] kallsyms: avoid hardcoding the buffer size
Date
From: Boqun Feng <boqun.feng@gmail.com>

This makes it easier to update the size later on.

Furthermore, a static assert is added to ensure both are updated
when that happens. The relationship used is one that keeps the new
size (512+1) close to the original buffer size (500).

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
This is a prerequisite patch, independently submitted at:

https://lore.kernel.org/lkml/20220506203443.24721-2-ojeda@kernel.org/

scripts/kallsyms.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 8caabddf817c..82d6508bdf29 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -27,8 +27,18 @@

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))

+#define _stringify_1(x) #x
+#define _stringify(x) _stringify_1(x)
+
#define KSYM_NAME_LEN 128

+/* A substantially bigger size than the current maximum. */
+#define KSYM_NAME_LEN_BUFFER 512
+_Static_assert(
+ KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
+ "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"
+);
+
struct sym_entry {
unsigned long long addr;
unsigned int len;
@@ -197,15 +207,15 @@ static void check_symbol_range(const char *sym, unsigned long long addr,

static struct sym_entry *read_symbol(FILE *in)
{
- char name[500], type;
+ char name[KSYM_NAME_LEN_BUFFER+1], type;
unsigned long long addr;
unsigned int len;
struct sym_entry *sym;
int rc;

- rc = fscanf(in, "%llx %c %499s\n", &addr, &type, name);
+ rc = fscanf(in, "%llx %c %" _stringify(KSYM_NAME_LEN_BUFFER) "s\n", &addr, &type, name);
if (rc != 3) {
- if (rc != EOF && fgets(name, 500, in) == NULL)
+ if (rc != EOF && fgets(name, sizeof(name), in) == NULL)
fprintf(stderr, "Read error or end of file.\n");
return NULL;
}
--
2.36.1
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