Messages in this thread | | | Subject | Re: [PATCH bpf-next] selftests/bpf: fix prog_tests/uprobe_autoattach compilation error | From | Daniel Borkmann <> | Date | Thu, 21 Apr 2022 18:53:22 +0200 |
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On 4/21/22 3:23 PM, Artem Savkov wrote: > I am getting the following compilation error for prog_tests/uprobe_autoattach.c > > tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c: In function ‘test_uprobe_autoattach’: > ./test_progs.h:209:26: error: pointer ‘mem’ may be used after ‘free’ [-Werror=use-after-free] > > mem variable is now used in one of the asserts so it shouldn't be freed right > away. Move free(mem) after the assert block.
Looks good, but I rephrased this a bit to avoid confusion. It's false positive given we only compare the addresses but don't deref mem, which the compiler might not be able to follow in this case.
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=6a12b8e20d7e72386594a9dbe7bf2d7fae3b3aa6
Thanks, Daniel
> Fixes: 1717e248014c ("selftests/bpf: Uprobe tests should verify param/return values") > Signed-off-by: Artem Savkov <asavkov@redhat.com> > --- > tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c b/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c > index d6003dc8cc99..35b87c7ba5be 100644 > --- a/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c > +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c > @@ -34,7 +34,6 @@ void test_uprobe_autoattach(void) > > /* trigger & validate shared library u[ret]probes attached by name */ > mem = malloc(malloc_sz); > - free(mem); > > ASSERT_EQ(skel->bss->uprobe_byname_parm1, trigger_val, "check_uprobe_byname_parm1"); > ASSERT_EQ(skel->bss->uprobe_byname_ran, 1, "check_uprobe_byname_ran"); > @@ -44,6 +43,8 @@ void test_uprobe_autoattach(void) > ASSERT_EQ(skel->bss->uprobe_byname2_ran, 3, "check_uprobe_byname2_ran"); > ASSERT_EQ(skel->bss->uretprobe_byname2_rc, mem, "check_uretprobe_byname2_rc"); > ASSERT_EQ(skel->bss->uretprobe_byname2_ran, 4, "check_uretprobe_byname2_ran"); > + > + free(mem); > cleanup: > test_uprobe_autoattach__destroy(skel); > } >
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