linux-kernel - [for-next][PATCH 1/4] ftrace: Test mcount_loc addr before calling ftrace_call

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Message-ID: <20250226010616.432688791@goodmis.org>
Date: Tue, 25 Feb 2025 20:05:57 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Masahiro Yamada <masahiroy@...nel.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Will Deacon <will@...nel.org>,
 Mark Brown <broonie@...nel.org>,
 Nathan Chancellor <nathan@...nel.org>,
 "Arnd Bergmann" <arnd@...db.de>
Subject: [for-next][PATCH 1/4] ftrace: Test mcount_loc addr before calling ftrace_call_addr()

From: Steven Rostedt <rostedt@...dmis.org>

The addresses in the mcount_loc can be zeroed and then moved by KASLR
making them invalid addresses. ftrace_call_addr() for ARM 64 expects a
valid address to kernel text. If the addr read from the mcount_loc section
is invalid, it must not call ftrace_call_addr(). Move the addr check
before calling ftrace_call_addr() in ftrace_process_locs().

Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Masahiro Yamada <masahiroy@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mark Brown <broonie@...nel.org>
Link: https://lore.kernel.org/20250225182054.290128736@goodmis.org
Fixes: ef378c3b8233 ("scripts/sorttable: Zero out weak functions in mcount_loc table")
Reported-by: Nathan Chancellor <nathan@...nel.org>
Reported-by: "Arnd Bergmann" <arnd@...db.de>
Tested-by: Nathan Chancellor <nathan@...nel.org>
Closes: https://lore.kernel.org/all/20250225025631.GA271248@ax162/
Closes: https://lore.kernel.org/all/91523154-072b-437b-bbdc-0b70e9783fd0@app.fastmail.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/ftrace.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 27c8def2139d..183f72cf15ed 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -7063,7 +7063,9 @@ static int ftrace_process_locs(struct module *mod,
 	pg = start_pg;
 	while (p < end) {
 		unsigned long end_offset;
-		addr = ftrace_call_adjust(*p++);
+
+		addr = *p++;
+
 		/*
 		 * Some architecture linkers will pad between
 		 * the different mcount_loc sections of different
@@ -7075,6 +7077,8 @@ static int ftrace_process_locs(struct module *mod,
 			continue;
 		}
 
+		addr = ftrace_call_adjust(addr);
+
 		end_offset = (pg->index+1) * sizeof(pg->records[0]);
 		if (end_offset > PAGE_SIZE << pg->order) {
 			/* We should have allocated enough */
-- 
2.47.2