From: Zheng Yejian <zhengyejian1@huawei.com>
To: <rostedt@goodmis.org>, <mhiramat@kernel.org>
Cc: <linux-kernel@vger.kernel.org>,
<linux-trace-kernel@vger.kernel.org>, <zhengyejian1@huawei.com>
Subject: [PATCH] tracing: Fix potential null-pointer-access of entry in list 'tr->err_log'
Date: Mon, 14 Nov 2022 18:46:32 +0800 [thread overview]
Message-ID: <20221114104632.3547266-1-zhengyejian1@huawei.com> (raw)
Entries in list 'tr->err_log' will be reused after entry number
exceed TRACING_LOG_ERRS_MAX.
The cmd string of the to be reused entry will be freed first then
allocated a new one. If the allocation failed, then the entry will
still be in list 'tr->err_log' but its 'cmd' field is set to be NULL,
later access of 'cmd' is risky.
Currently above problem can cause the loss of 'cmd' information of first
entry in 'tr->err_log'. When execute `cat /sys/kernel/tracing/error_log`,
reproduce logs like:
[ 37.495100] trace_kprobe: error: Maxactive is not for kprobe(null) ^
[ 38.412517] trace_kprobe: error: Maxactive is not for kprobe
Command: p4:myprobe2 do_sys_openat2
^
Fixes: 1581a884b7ca ("tracing: Remove size restriction on tracing_log_err cmd strings")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
---
kernel/trace/trace.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 47a44b055a1d..5ae776598106 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7802,6 +7802,7 @@ static struct tracing_log_err *get_tracing_log_err(struct trace_array *tr,
int len)
{
struct tracing_log_err *err;
+ char *cmd;
if (tr->n_err_log_entries < TRACING_LOG_ERRS_MAX) {
err = alloc_tracing_log_err(len);
@@ -7810,12 +7811,12 @@ static struct tracing_log_err *get_tracing_log_err(struct trace_array *tr,
return err;
}
-
+ cmd = kzalloc(len, GFP_KERNEL);
+ if (!cmd)
+ return ERR_PTR(-ENOMEM);
err = list_first_entry(&tr->err_log, struct tracing_log_err, list);
kfree(err->cmd);
- err->cmd = kzalloc(len, GFP_KERNEL);
- if (!err->cmd)
- return ERR_PTR(-ENOMEM);
+ err->cmd = cmd;
list_del(&err->list);
return err;
--
2.25.1
next reply other threads:[~2022-11-14 10:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-14 10:46 Zheng Yejian [this message]
2022-11-14 12:46 ` [PATCH] tracing: Fix potential null-pointer-access of entry in list 'tr->err_log' Masami Hiramatsu
2022-11-14 13:06 ` Zheng Yejian
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20221114104632.3547266-1-zhengyejian1@huawei.com \
--to=zhengyejian1@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).