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Reduce false positives from Static Analyzers

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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
This commit is contained in:
Richard Yao
2022-09-30 18:30:12 -04:00
committed by GitHub
parent dee8934e8f
commit 55d7afa4ad
19 changed files with 170 additions and 131 deletions
Download Patch File Download Diff File Expand all files Collapse all files
contrib/coverity/model.c
+29 -92
View File
@@ -31,66 +31,6 @@
int condition0, condition1;
void
abort()
{
__coverity_panic__();
}
void
exit(int status)
{
(void) status;
__coverity_panic__();
}
void
_exit(int status)
{
(void) status;
__coverity_panic__();
}
void
zed_log_die(const char *fmt, ...)
{
__coverity_format_string_sink__(fmt);
__coverity_panic__();
}
void
panic(const char *fmt, ...)
{
__coverity_format_string_sink__(fmt);
__coverity_panic__();
}
void
vpanic(const char *fmt, va_list adx)
{
(void) adx;
__coverity_format_string_sink__(fmt);
__coverity_panic__();
}
void
uu_panic(const char *format, ...)
{
__coverity_format_string_sink__(format);
__coverity_panic__();
}
int
libspl_assertf(const char *file, const char *func, int line,
const char *format, ...)
{
__coverity_format_string_sink__(format);
__coverity_panic__();
}
int
ddi_copyin(const void *from, void *to, size_t len, int flags)
{
@@ -125,7 +65,7 @@ umem_alloc_aligned(size_t size, size_t align, int kmflags)
{
(void) align;
if (UMEM_NOFAIL & kmflags == UMEM_NOFAIL)
if ((UMEM_NOFAIL & kmflags) == UMEM_NOFAIL)
return (__coverity_alloc__(size));
else if (condition0)
return (__coverity_alloc__(size));
@@ -136,7 +76,7 @@ umem_alloc_aligned(size_t size, size_t align, int kmflags)
void *
umem_alloc(size_t size, int kmflags)
{
if (UMEM_NOFAIL & kmflags == UMEM_NOFAIL)
if ((UMEM_NOFAIL & kmflags) == UMEM_NOFAIL)
return (__coverity_alloc__(size));
else if (condition0)
return (__coverity_alloc__(size));
@@ -147,7 +87,7 @@ umem_alloc(size_t size, int kmflags)
void *
umem_zalloc(size_t size, int kmflags)
{
if (UMEM_NOFAIL & kmflags == UMEM_NOFAIL)
if ((UMEM_NOFAIL & kmflags) == UMEM_NOFAIL)
return (__coverity_alloc__(size));
else if (condition0)
return (__coverity_alloc__(size));
@@ -163,6 +103,32 @@ umem_free(void *buf, size_t size)
__coverity_free__(buf);
}
typedef struct {} umem_cache_t;
void *
umem_cache_alloc(umem_cache_t *skc, int flags)
{
(void) skc;
if (condition1)
__coverity_sleep__();
if ((UMEM_NOFAIL & flags) == UMEM_NOFAIL)
return (__coverity_alloc_nosize__());
else if (condition0)
return (__coverity_alloc_nosize__());
else
return (NULL);
}
void
umem_cache_free(umem_cache_t *skc, void *obj)
{
(void) skc;
__coverity_free__(obj);
}
void *
spl_kmem_alloc(size_t sz, int fl, const char *func, int line)
{
@@ -243,13 +209,6 @@ free(void *buf)
__coverity_free__(buf);
}
int
spl_panic(const char *file, const char *func, int line, const char *fmt, ...)
{
__coverity_format_string_sink__(fmt);
__coverity_panic__();
}
int
sched_yield(void)
{
@@ -398,25 +357,3 @@ __cond_resched(void)
__coverity_sleep__();
}
}
/*
* An endian-independent filesystem must support doing byte swaps on data. We
* attempt to suppress taint warnings, which are false positives for us.
*/
void
byteswap_uint64_array(void *vbuf, size_t size)
{
__coverity_tainted_data_sanitize__(vbuf);
}
void
byteswap_uint32_array(void *vbuf, size_t size)
{
__coverity_tainted_data_sanitize__(vbuf);
}
void
byteswap_uint16_array(void *vbuf, size_t size)
{
__coverity_tainted_data_sanitize__(vbuf);
}