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tracing: fprobe: Fix infinite recursion using preempt_*_notrace()

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commit a3e892ab0f upstream.

Since preempt_count_add/del() are tracable functions, it is not allowed
to use preempt_disable/enable() in ftrace handlers. Without this fix,
probing on `preempt_count_add%return` will cause an infinite recursion
of fprobes.

To fix this problem, use preempt_disable/enable_notrace() in
fprobe_return().

Link: https://lore.kernel.org/all/175374642359.1471729.1054175011228386560.stgit@mhiramat.tok.corp.google.com/

Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Masami Hiramatsu (Google)
2025-07-29 08:47:03 +09:00
committed by Greg Kroah-Hartman
parent 71bb5d8af0
commit 3d95aed41f
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/fprobe.c
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@@ -352,7 +352,7 @@ static void fprobe_return(struct ftrace_graph_ret *trace,
size_words = SIZE_IN_LONG(size);
ret_ip = ftrace_regs_get_instruction_pointer(fregs);
preempt_disable();
preempt_disable_notrace();
curr = 0;
while (size_words > curr) {
@@ -368,7 +368,7 @@ static void fprobe_return(struct ftrace_graph_ret *trace,
}
curr += size;
}
preempt_enable();
preempt_enable_notrace();
}
NOKPROBE_SYMBOL(fprobe_return);