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Message-ID: <20221117171730.023c8472@gandalf.local.home>
Date: Thu, 17 Nov 2022 17:17:30 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Xiu Jianfeng <xiujianfeng@...wei.com>
Cc: <mhiramat@...nel.org>, <mark.rutland@....com>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: Fix null pointer dereference in
ftrace_add_mod()
On Wed, 16 Nov 2022 09:52:07 +0800
Xiu Jianfeng <xiujianfeng@...wei.com> wrote:
> The @ftrace_mod is allocated by kzalloc(), so both the members {prev,next}
> of @ftrace_mode->list are NULL, it's not a valid state to call list_del().
> If kstrdup() for @ftrace_mod->{func|module} fails, it goes to @out_free
> tag and calls free_ftrace_mod() to destroy @ftrace_mod, then list_del()
> will write prev->next and next->prev, where null pointer dereference
> happens.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000008
> Oops: 0002 [#1] PREEMPT SMP NOPTI
> Call Trace:
> <TASK>
> ftrace_mod_callback+0x20d/0x220
> ? do_filp_open+0xd9/0x140
> ftrace_process_regex.isra.51+0xbf/0x130
> ftrace_regex_write.isra.52.part.53+0x6e/0x90
> vfs_write+0xee/0x3a0
> ? __audit_filter_op+0xb1/0x100
> ? auditd_test_task+0x38/0x50
> ksys_write+0xa5/0xe0
> do_syscall_64+0x3a/0x90
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> Kernel panic - not syncing: Fatal exception
>
> So call INIT_LIST_HEAD() to initialize the list member to fix this issue.
>
> Fixes: 673feb9d76ab ("ftrace: Add :mod: caching infrastructure to trace_array")
> Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
> ---
Queued. Thanks Xiu!
-- Steve
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