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author | Zhou Chengming <zhouchengming1@huawei.com> | 2017-11-02 09:18:21 +0800 |
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committer | Ingo Molnar <mingo@kernel.org> | 2017-11-07 12:20:09 +0100 |
commit | e846d13958066828a9483d862cc8370a72fadbb6 (patch) | |
tree | 4ee0e7c3f4b1eec670b0edf57dac66e201f49658 /Documentation/x86 | |
parent | d786f05175fae09cc39dfa5769c62649341caeb4 (diff) | |
download | linux-e846d13958066828a9483d862cc8370a72fadbb6.tar.bz2 |
kprobes, x86/alternatives: Use text_mutex to protect smp_alt_modules
We use alternatives_text_reserved() to check if the address is in
the fixed pieces of alternative reserved, but the problem is that
we don't hold the smp_alt mutex when call this function. So the list
traversal may encounter a deleted list_head if another path is doing
alternatives_smp_module_del().
One solution is that we can hold smp_alt mutex before call this
function, but the difficult point is that the callers of this
functions, arch_prepare_kprobe() and arch_prepare_optimized_kprobe(),
are called inside the text_mutex. So we must hold smp_alt mutex
before we go into these arch dependent code. But we can't now,
the smp_alt mutex is the arch dependent part, only x86 has it.
Maybe we can export another arch dependent callback to solve this.
But there is a simpler way to handle this problem. We can reuse the
text_mutex to protect smp_alt_modules instead of using another mutex.
And all the arch dependent checks of kprobes are inside the text_mutex,
so it's safe now.
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Fixes: 2cfa197 "ftrace/alternatives: Introducing *_text_reserved functions"
Link: http://lkml.kernel.org/r/1509585501-79466-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/x86')
0 files changed, 0 insertions, 0 deletions