From: Zheng Yejian zhengyejian1@huawei.com
[ Upstream commit 067df9e0ad48a97382ab2179bbe773a13a846028 ]
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 ^
Link: https://lore.kernel.org/linux-trace-kernel/20221114104632.3547266-1-zhengyej...
Fixes: 1581a884b7ca ("tracing: Remove size restriction on tracing_log_err cmd strings") Signed-off-by: Zheng Yejian zhengyejian1@huawei.com Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 87d2f04152f9..7132e21e90d6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7803,6 +7803,7 @@ 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); @@ -7811,12 +7812,12 @@ 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;