| Message ID | 20220426122531.1506634-1-colin.i.king@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [V2] selftests/resctrl: Fix null pointer dereference on open failed | expand |
On 4/26/22 6:25 AM, Colin Ian King wrote: > 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> > --- > > V2: Add cppcheck analysis information > > --- > 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); > > Thank you. Applied to linux-kselftest next for Linux 5.19-rc1 thanks, -- Shuah
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);
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> --- V2: Add cppcheck analysis information --- tools/testing/selftests/resctrl/fill_buf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)