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SubjectRe: [PATCH v2] perf probe: Added protection to avoid endless loop
On Wed,  3 Feb 2021 22:57:02 +0800
Jianlin Lv <Jianlin.Lv@arm.com> wrote:

> if dwarf_offdie() return NULL, the continue statement forces the next
> iteration of the loop without update variable off. It will cause an
> endless loop in the process of traversing the compilation unit.
> So added exception protection for loop CUs.
>

Thanks for the quick update!

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>
> ---
> v2: removed the statement that updates variable in the function argument.
> ---
> tools/perf/util/probe-finder.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 76dd349aa48d..1b118c9c86a6 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1187,8 +1187,10 @@ static int debuginfo__find_probe_location(struct debuginfo *dbg,
> while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
> /* Get the DIE(Debugging Information Entry) of this CU */
> diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
> - if (!diep)
> + if (!diep) {
> + off = noff;
> continue;
> + }
>
> /* Check if target file is included. */
> if (pp->file)
> @@ -1949,8 +1951,10 @@ int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
>
> /* Get the DIE(Debugging Information Entry) of this CU */
> diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
> - if (!diep)
> + if (!diep) {
> + off = noff;
> continue;
> + }
>
> /* Check if target file is included. */
> if (lr->file)
> --
> 2.25.1
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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