diff options
| author | Eugene Syromyatnikov <evgsyr@gmail.com> | 2022-06-28 16:55:49 +0200 |
|---|---|---|
| committer | Dmitry V. Levin <ldv@strace.io> | 2022-06-28 15:37:06 +0000 |
| commit | 6d3e97e83a7d61cbb2f5109efb4b519383a55712 (patch) | |
| tree | f60be0522faa4d057690c15053c3517239bc50b6 | |
| parent | 968789d5426442ac43b96eabd65f3e5c0c141e62 (diff) | |
| download | strace-6d3e97e83a7d61cbb2f5109efb4b519383a55712.tar.gz | |
util: add offs sanity check to print_clock_t
While it is not strictly needed right now, the code that uses
the calculated offs value lacks any checks for possible buf overruns,
which is not defensive enough, so let's add them. Reported by covscan:
Error: OVERRUN (CWE-119):
strace-5.18/src/util.c:248: assignment: Assigning:
"offs" = "ilog10(val / clk_tck)". The value of "offs" is now between
16 and 31 (inclusive).
strace-5.18/src/util.c:249: overrun-local: Overrunning array of 30 bytes
at byte offset 31 by dereferencing pointer "buf + offs". [Note: The source
code implementation of the function has been overridden by a builtin model.]
Error: OVERRUN (CWE-119):
strace-5.18/src/util.c:248: assignment: Assigning:
"offs" = "ilog10(val / clk_tck)". The value of "offs" is now between
16 and 31 (inclusive).
strace-5.18/src/util.c:253: overrun-buffer-arg: Overrunning array "buf"
of 30 bytes by passing it to a function which accesses it at byte offset
32 using argument "offs + 2UL" (which evaluates to 33). [Note: The source
code implementation of the function has been overridden by a builtin model.]
Error: OVERRUN (CWE-119):
strace-5.18/src/util.c:248: assignment: Assigning:
"offs" = "ilog10(val / clk_tck)". The value of "offs" is now between
16 and 31 (inclusive).
strace-5.18/src/util.c:254: overrun-local: Overrunning array "buf"
of 30 bytes at byte offset 32 using index "offs + 1UL" (which evaluates
to 32).
* src/util.c (print_clock_t): Add check that offs is small enough
for it and "offs + 2" not to overrun buf.
| -rw-r--r-- | src/util.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/util.c b/src/util.c index 5f87acb91..93aa7b371 100644 --- a/src/util.c +++ b/src/util.c @@ -246,6 +246,14 @@ print_clock_t(uint64_t val) */ char buf[sizeof(uint64_t) * 3 + sizeof("0.0 s")]; size_t offs = ilog10(val / clk_tck); + /* + * This check is mostly to appease covscan, which thinks + * that offs can go as high as 31 (it cannot), but since + * there is no proper sanity checks against offs overrunning + * buf down the code, it may as well be here. + */ + if (offs > (sizeof(buf) - sizeof("0.0 s"))) + return; int ret = snprintf(buf + offs, sizeof(buf) - offs, "%.*f s", frac_width, (double) (val % clk_tck) / clk_tck); |