From: Colin Ian King colin.i.king@gmail.com
[ Upstream commit c7b607fa9325ccc94982774c505176677117689c ]
Currently if opening /dev/null fails to open then file pointer fp is null and further access to fp via fprintf will cause a null pointer dereference. Fix this by returning a negative error value when a null fp is detected.
Detected using cppcheck static analysis: tools/testing/selftests/resctrl/fill_buf.c:124:6: note: Assuming that condition '!fp' is not redundant if (!fp) ^ tools/testing/selftests/resctrl/fill_buf.c:126:10: note: Null pointer dereference fprintf(fp, "Sum: %d ", ret);
Fixes: a2561b12fe39 ("selftests/resctrl: Add built in benchmark") Signed-off-by: Colin Ian King colin.i.king@gmail.com Signed-off-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/resctrl/fill_buf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/resctrl/fill_buf.c b/tools/testing/selftests/resctrl/fill_buf.c index 51e5cf22632f..56ccbeae0638 100644 --- a/tools/testing/selftests/resctrl/fill_buf.c +++ b/tools/testing/selftests/resctrl/fill_buf.c @@ -121,8 +121,10 @@ static int fill_cache_read(unsigned char *start_ptr, unsigned char *end_ptr,
/* Consume read result so that reading memory is not optimized out. */ fp = fopen("/dev/null", "w"); - if (!fp) + if (!fp) { perror("Unable to write to /dev/null"); + return -1; + } fprintf(fp, "Sum: %d ", ret); fclose(fp);