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kallsyms: fix symbol type for "big" symbols

PATCH New Miguel Ojeda 1 participant 1 message Nov 7, 2025

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Miguel Ojeda

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PATCH 1/1 kallsyms: fix symbol type for "big" symbols

kallsyms_get_symbol_type() does not take into account the potential extra byte for "big" symbols.

This makes /proc/kallsyms output the wrong symbol type for such "big" symbols, such as a bogus 1 symbol type, which in turn confused other tooling [1].

Thus fix it.

Cc [email protected]
Link https://lore.kernel.org/all/CANiq72ns1sRukpX-4L3FgqfJw4nXZ5AyqQKCEeQ=nhyERG7QGA@mail.gmail.com/ open here
Fixes 73bbb94466fd ("kallsyms: support "big" kernel symbols")
Signed-off-by Miguel Ojeda <[email protected]>

---
Somehow this went unnoticed so far... In Fedora 42 I compared the System.map with /proc/kallsyms and that was the only symbol with a different type -- Arnaldo, could you please confirm this makes it go away for you? Thanks!

 kernel/kallsyms.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)
kernel/kallsyms.c +11 -1
index 1e7635864124..4f9b612d6bf2 100644
@@ -101,11 +101,21 @@ static unsigned int kallsyms_expand_symbol(unsigned int off,
  */
 static char kallsyms_get_symbol_type(unsigned int off)
 {
+	const u8 len = kallsyms_names[off];
+
+	off++;
+
+	/*
+	 * If MSB is 1, it is a "big" symbol, so we need to skip two bytes.
+	 */
+	if ((len & 0x80) != 0)
+		off++;
+
 	/*
 	 * Get just the first code, look it up in the token table,
 	 * and return the first char from this token.
 	 */
-	return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
+	return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off]]];
 }

base-commit: dc77806cf3b4788d328fddf245e86c5b529f31a2 --
2.51.2