Messages in this thread | | | Date | Fri, 7 Jun 2019 09:52:58 +0800 | From | Gen Zhang <> | Subject | Re: [PATCH] clk: fix a missing-free bug in clk_cpy_name() |
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On Thu, Jun 06, 2019 at 01:16:45PM -0700, Stephen Boyd wrote: > Quoting Gen Zhang (2019-06-05 09:00:43) > > On Wed, Jun 05, 2019 at 08:38:00AM +0200, Jiri Slaby wrote: > > > On 31. 05. 19, 3:14, Gen Zhang wrote: > > > > In clk_cpy_name(), '*dst_p'('parent->name'and 'parent->fw_name') and > > > > 'dst' are allcoted by kstrdup_const(). According to doc: "Strings > > > > allocated by kstrdup_const should be freed by kfree_const". So > > > > 'parent->name', 'parent->fw_name' and 'dst' should be freed. > > > > > > > > Signed-off-by: Gen Zhang <blackgod016574@gmail.com> > > > > --- > > > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > > > > index aa51756..85c4d3f 100644 > > > > --- a/drivers/clk/clk.c > > > > +++ b/drivers/clk/clk.c > > > > @@ -3435,6 +3435,7 @@ static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist) > > > > if (!dst) > > > > return -ENOMEM; > > > > > > > > + kfree_const(dst); > > > > > > So you are now returning a freed pointer in dst_p? > > Thanks for your reply. I re-examined the code, and this kfree is > > incorrect and it should be deleted. > > > > > > > return 0; > > > > } > > > > > > > > @@ -3491,6 +3492,8 @@ static int clk_core_populate_parent_map(struct clk_core *core) > > > > kfree_const(parents[i].name); > > > > kfree_const(parents[i].fw_name); > > > > } while (--i >= 0); > > > > + kfree_const(parent->name); > > > > + kfree_const(parent->fw_name); > > > > > > Both of them were just freed in the loop above, no? > > for (i = 0, parent = parents; i < num_parents; i++, parent++) > > Is 'parent' the same as the one from the loop above? > > Yes. Did it change somehow? parent++? > > > > > Moreover, should 'parents[i].name' and 'parents[i].fw_name' be freed by > > kfree_const()? > > > > Yes? They're allocated with kstrdup_const() in clk_cpy_name(), or > they're NULL by virtue of the kcalloc and then kfree_const() does > nothing. I re-examined clk_cpy_name(). They are the second parameter of clk_cpy_name(). The first parameter is allocated, not the second one. So 'parent->name' and 'parent->fw_name' should be freed, not 'parents[i].name' or 'parents[i].fw_name'. Am I totally misunderstanding this clk_cpy_name()? :-(
Thanks Gen > > I'm having a hard time following what this patch is trying to fix. It > looks unnecessary though so I'm going to drop it from the clk review > queue. >
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