| Message ID | b595166b7ece013b371c2bac1098533f1ffa12d0.1743438749.git.namcao@linutronix.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests: coredump: Some bug fixes | expand |
On 2025-03-31, Nam Cao <namcao@linutronix.de> wrote: > The buffer pointer "line" is not initialized. This pointer is passed to > getline(). Ouch. > It can still work if the stack is zero-initialized, because getline() can > work with a NULL pointer as buffer. > > But this is obviously broken. This bug shows up while running the test on a > riscv64 machine. > > Fix it by properly initializing the pointer. > > Fixes: 15858da53542 ("selftests: coredump: Add stackdump test") > Signed-off-by: Nam Cao <namcao@linutronix.de> > --- > tools/testing/selftests/coredump/stackdump_test.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c > index 137b2364a082..1dc54e128586 100644 > --- a/tools/testing/selftests/coredump/stackdump_test.c > +++ b/tools/testing/selftests/coredump/stackdump_test.c > @@ -100,6 +100,8 @@ TEST_F(coredump, stackdump) > FILE *file; > pid_t pid; > > + line = NULL; The syntax of getline(3) is quite interesting, since it allocates/reallocates/uses the lineptr as needed and possibly requires the application to free the data. I recommend moving the initialization down to the getline() call and also add the corresponding free(). Something like this: diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c index 137b2364a082..c23cf95c3f6d 100644 --- a/tools/testing/selftests/coredump/stackdump_test.c +++ b/tools/testing/selftests/coredump/stackdump_test.c @@ -138,10 +138,12 @@ TEST_F(coredump, stackdump) ASSERT_NE(file, NULL); /* Step 4: Make sure all stack pointer values are non-zero */ + line = NULL; for (i = 0; -1 != getline(&line, &line_length, file); ++i) { stack = strtoull(line, NULL, 10); ASSERT_NE(stack, 0); } + free(line); ASSERT_EQ(i, 1 + NUM_THREAD_SPAWN); Because of how getline() works, technically your patch is good enough. But we should probably excercise more precision in the use of getline() so as to set a good example. John Ogness
diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c index 137b2364a082..1dc54e128586 100644 --- a/tools/testing/selftests/coredump/stackdump_test.c +++ b/tools/testing/selftests/coredump/stackdump_test.c @@ -100,6 +100,8 @@ TEST_F(coredump, stackdump) FILE *file; pid_t pid; + line = NULL; + /* * Step 1: Setup core_pattern so that the stackdump script is executed when the child * process crashes
The buffer pointer "line" is not initialized. This pointer is passed to getline(). It can still work if the stack is zero-initialized, because getline() can work with a NULL pointer as buffer. But this is obviously broken. This bug shows up while running the test on a riscv64 machine. Fix it by properly initializing the pointer. Fixes: 15858da53542 ("selftests: coredump: Add stackdump test") Signed-off-by: Nam Cao <namcao@linutronix.de> --- tools/testing/selftests/coredump/stackdump_test.c | 2 ++ 1 file changed, 2 insertions(+)