When reviewing Clang Static Analyzer reports against a branch that had
experimental header changes based on the Coverity model file to inform
it that KM_SLEEP allocations cannot return NULL, I found a report saying
that a KM_PUSHPAGE allocation returned NULL. The actual implementation
does not return NULL unless KM_NOSLEEP has been passed, so we backport
the correction from the experimental header changes to the Coverity
model.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes#14210
Upon review, it was found that the model for malloc() was incorrect.
In addition, several general purpose memory allocation functions were
missing models:
* kmem_vasprintf()
* kmem_asprintf()
* kmem_strdup()
* kmem_strfree()
* spl_vmem_alloc()
* spl_vmem_zalloc()
* spl_vmem_free()
* calloc()
As an experiment to try to find more bugs, some less than general
purpose memory allocation functions were also given models:
* zfsvfs_create()
* zfsvfs_free()
* nvlist_alloc()
* nvlist_dup()
* nvlist_free()
* nvlist_pack()
* nvlist_unpack()
Finally, the models were improved using additional coverity primitives:
* __coverity_negative_sink__()
* __coverity_writeall0__()
* __coverity_mark_as_uninitialized_buffer__()
* __coverity_mark_as_afm_allocated__()
In addition, an attempt to inform coverity that certain modelled
functions read entire buffers was used by adding the following to
certain models:
int first = buf[0];
int last = buf[buflen-1];
It was inspired by the QEMU model file.
No additional false positives were found by this, but it is believed
that the more accurate model file will help to catch false positives in
the future.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes#14048
Both Clang's Static Analyzer and Synopsys' Coverity would ignore
assertions. Following Clang's advice, we annotate our assertions:
https://clang-analyzer.llvm.org/annotations.html#custom_assertions
This makes both Clang's Static Analyzer and Coverity properly identify
assertions. This change reduced Clang's reported defects from 246 to
180. It also reduced the false positives reported by Coverityi by 10,
while enabling Coverity to find 9 more defects that previously were
false negatives.
A couple examples of this would be CID-1524417 and CID-1524423. After
submitting a build to coverity with the modified assertions, CID-1524417
disappeared while the report for CID-1524423 no longer claimed that the
assertion tripped.
Coincidentally, it turns out that it is possible to more accurately
annotate our headers than the Coverity modelling file permits in the
case of format strings. Since we can do that and this patch annotates
headers whenever `__coverity_panic__()` would have been used in the
model file, we drop all models that use `__coverity_panic__()` from the
model file.
Upon seeing the success in eliminating false positives involving
assertions, it occurred to me that we could also modify our headers to
eliminate coverity's false positives involving byte swaps. We now have
coverity specific byteswap macros, that do nothing, to disable
Coverity's false positives when we do byte swaps. This allowed us to
also drop the byteswap definitions from the model file.
Lastly, a model file update has been done beyond the mentioned
deletions:
* The definitions of `umem_alloc_aligned()`, `umem_alloc()` andi
`umem_zalloc()` were originally implemented in a way that was
intended to inform coverity that when KM_SLEEP has been passed these
functions, they do not return NULL. A small error in how this was
done was found, so we correct it.
* Definitions for umem_cache_alloc() and umem_cache_free() have been
added.
In practice, no false positives were avoided by making these changes,
but in the interest of correctness from future coverity builds, we make
them anyway.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes#13902
`uu_panic()` needs to be modelled and the definition of `vpanic()` from
the original coverity model was missing
`__coverity_format_string_sink__()`.
We also model `libspl_assertf()` as part of an attempt to eliminate
false positives.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes#13901
Other projects such as the python project include their coverity models
in their repositories. This provides transparency, which is beneficial
in open source projects. Therefore, it is a good idea to include the
coverity model in our repository too.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes#13884
