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selftests/resctrl: Fix null pointer dereference on open failed

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[ 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>
This commit is contained in:
Colin Ian King 2022-04-26 13:25:31 +01:00 committed by Greg Kroah-Hartman
parent c54d66c514
commit 97b56f17b3
1 changed files with 3 additions and 1 deletions
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4
tools/testing/selftests/resctrl/fill_buf.c
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@ -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);