From c7b607fa9325ccc94982774c505176677117689c Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Tue, 26 Apr 2022 13:25:31 +0100 Subject: [PATCH] selftests/resctrl: Fix null pointer dereference on open failed 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 Signed-off-by: Shuah Khan --- 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 51e5cf2..56ccbea 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); -- 2.7.4