linux-kernel - [PATCH v4] tracing: precise log info for kretprobe addr err

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 27 Jan 2021 23:15:07 +0800
From:   Jianlin Lv <Jianlin.Lv@....com>
To:     rostedt@...dmis.org, mingo@...hat.com, mhiramat@...nel.org,
        oleg@...hat.com
Cc:     Jianlin.Lv@....com, linux-kernel@...r.kernel.org
Subject: [PATCH v4] tracing: precise log info for kretprobe addr err

When trying to create kretprobe with the wrong function symbol in tracefs;
The error is triggered in the register_trace_kprobe() and recorded as
FAIL_REG_PROBE issue,

Example:
  $ cd /sys/kernel/debug/tracing
  $ echo 'r:myprobe ERROR_SYMBOL_XXX ret=%x0' >> kprobe_events
    bash: echo: write error: Invalid argument
  $ cat error_log
    [142797.347877] trace_kprobe: error: Failed to register probe event
    Command: r:myprobe ERROR_SYMBOL_XXX ret=%x0
                       ^

This error can be detected in the parameter parsing stage, the effect of
applying this patch is as follows:

  $ echo 'r:myprobe ERROR_SYMBOL_XXX ret=%x0' >> kprobe_events
    bash: echo: write error: Invalid argument
  $ cat error_log
    [415.89]trace_kprobe: error: Retprobe address must be an function entry
    Command: r:myprobe ERROR_SYMBOL_XXX ret=%x0
                       ^
v2 changes:
- Added !strchr(symbol, ':') to check whether symbol is really bad
  or from a module.

Signed-off-by: Jianlin Lv <Jianlin.Lv@....com>
---
v2: added !strchr(symbol, ':') to check really bad symbol or from module.
v4: added changelog and code comments.
---
 kernel/trace/trace_kprobe.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e6fba1798771..384208a38f82 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -830,7 +830,8 @@ static int trace_kprobe_create(int argc, const char *argv[])
 			flags |= TPARG_FL_RETURN;
 		if (kprobe_on_func_entry(NULL, symbol, offset))
 			flags |= TPARG_FL_FENTRY;
-		if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {
+		/* Check whether symbol is really bad or from a module */
+		if (!strchr(symbol, ':') && is_return && !(flags & TPARG_FL_FENTRY)) {
 			trace_probe_log_err(0, BAD_RETPROBE);
 			goto parse_error;
 		}
-- 
2.25.1