https://github.com/torvalds/linux
Revision 067df9e0ad48a97382ab2179bbe773a13a846028 authored by Zheng Yejian on 14 November 2022, 10:46:32 UTC, committed by Steven Rostedt (Google) on 18 November 2022, 01:41:01 UTC
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-zhengyejian1@huawei.com

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>
1 parent b875206
History
Tip revision: 067df9e0ad48a97382ab2179bbe773a13a846028 authored by Zheng Yejian on 14 November 2022, 10:46:32 UTC
tracing: Fix potential null-pointer-access of entry in list 'tr->err_log'
Tip revision: 067df9e
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