[PATCH v1 2/7] selftests/powerpc: Add ptrace setup_core_pattern() null-terminator

[Benjamin Gray]

- malloc() does not zero the buffer,
- fread() does not null-terminate it's output,
- `cat /proc/sys/kernel/core_pattern | hexdump -C` shows the file is
  not inherently null-terminated

So using string operations on the buffer is risky. Explicitly add a null
character to the end to make it safer.
---
 tools/testing/selftests/powerpc/ptrace/core-pkey.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/powerpc/ptrace/core-pkey.c 
b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
index bbc05ffc5860..5c82ed9e7c65 100644
--- a/tools/testing/selftests/powerpc/ptrace/core-pkey.c
+++ b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
@@ -383,7 +383,7 @@ static int setup_core_pattern(char **core_pattern_, bool 
*changed_)
                goto out;
        }
 
-       ret = fread(core_pattern, 1, PATH_MAX, f);
+       ret = fread(core_pattern, 1, PATH_MAX - 1, f);
        fclose(f);
        if (!ret) {
                perror("Error reading core_pattern file");
@@ -391,6 +391,8 @@ static int setup_core_pattern(char **core_pattern_, bool 
*changed_)
                goto out;
        }
 
+       core_pattern[ret] = '\0';
+
        /* Check whether we can predict the name of the core file. */
        if (!strcmp(core_pattern, "core") || !strcmp(core_pattern, "core.%p"))
                *changed_ = false;
-- 
2.38.1