[pushed] analyzer: fix deref-before-check false positives due to inlining [PR112790]
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Commit Message
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Successful run of analyzer integration tests on x86_64-pc-linux-gnu.
Pushed to trunk as r14-6918-g5743e1899d5964.
gcc/analyzer/ChangeLog:
PR analyzer/112790
* checker-event.cc (class inlining_info): Move to...
* inlining-iterator.h (class inlining_info): ...here.
* sm-malloc.cc: Include "analyzer/inlining-iterator.h".
(maybe_complain_about_deref_before_check): Reject stmts that were
inlined from another function.
gcc/testsuite/ChangeLog:
PR analyzer/112790
* c-c++-common/analyzer/deref-before-check-pr112790.c: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
---
gcc/analyzer/checker-event.cc | 40 -------------------
gcc/analyzer/inlining-iterator.h | 40 +++++++++++++++++++
gcc/analyzer/sm-malloc.cc | 10 +++++
.../analyzer/deref-before-check-pr112790.c | 27 +++++++++++++
4 files changed, 77 insertions(+), 40 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/analyzer/deref-before-check-pr112790.c
@@ -106,46 +106,6 @@ event_kind_to_string (enum event_kind ek)
}
}
-/* A class for fixing up fndecls and stack depths in checker_event, based
- on inlining records.
-
- The early inliner runs before the analyzer, which can lead to confusing
- output.
-
- Tne base fndecl and depth within a checker_event are from call strings
- in program_points, which reflect the call strings after inlining.
- This class lets us offset the depth and fix up the reported fndecl and
- stack depth to better reflect the user's original code. */
-
-class inlining_info
-{
-public:
- inlining_info (location_t loc)
- {
- inlining_iterator iter (loc);
- m_inner_fndecl = iter.get_fndecl ();
- int num_frames = 0;
- while (!iter.done_p ())
- {
- m_outer_fndecl = iter.get_fndecl ();
- num_frames++;
- iter.next ();
- }
- if (num_frames > 1)
- m_extra_frames = num_frames - 1;
- else
- m_extra_frames = 0;
- }
-
- tree get_inner_fndecl () const { return m_inner_fndecl; }
- int get_extra_frames () const { return m_extra_frames; }
-
-private:
- tree m_outer_fndecl;
- tree m_inner_fndecl;
- int m_extra_frames;
-};
-
/* class checker_event : public diagnostic_event. */
/* checker_event's ctor. */
@@ -106,4 +106,44 @@ private:
tree m_next_abstract_origin;
};
+/* A class for fixing up fndecls and stack depths in checker_event, based
+ on inlining records.
+
+ The early inliner runs before the analyzer, which can lead to confusing
+ output.
+
+ Tne base fndecl and depth within a checker_event are from call strings
+ in program_points, which reflect the call strings after inlining.
+ This class lets us offset the depth and fix up the reported fndecl and
+ stack depth to better reflect the user's original code. */
+
+class inlining_info
+{
+public:
+ inlining_info (location_t loc)
+ {
+ inlining_iterator iter (loc);
+ m_inner_fndecl = iter.get_fndecl ();
+ int num_frames = 0;
+ while (!iter.done_p ())
+ {
+ m_outer_fndecl = iter.get_fndecl ();
+ num_frames++;
+ iter.next ();
+ }
+ if (num_frames > 1)
+ m_extra_frames = num_frames - 1;
+ else
+ m_extra_frames = 0;
+ }
+
+ tree get_inner_fndecl () const { return m_inner_fndecl; }
+ int get_extra_frames () const { return m_extra_frames; }
+
+private:
+ tree m_outer_fndecl;
+ tree m_inner_fndecl;
+ int m_extra_frames;
+};
+
#endif /* GCC_ANALYZER_INLINING_ITERATOR_H */
@@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. If not see
#include "analyzer/program-state.h"
#include "analyzer/checker-event.h"
#include "analyzer/exploded-graph.h"
+#include "analyzer/inlining-iterator.h"
#if ENABLE_ANALYZER
@@ -2168,6 +2169,15 @@ maybe_complain_about_deref_before_check (sm_context *sm_ctxt,
if (checked_in_frame->get_index () > assumed_nonnull_in_frame->get_index ())
return;
+ /* Don't complain if STMT was inlined from another function, to avoid
+ similar false positives involving shared helper functions. */
+ if (stmt->location)
+ {
+ inlining_info info (stmt->location);
+ if (info.get_extra_frames () > 0)
+ return;
+ }
+
tree diag_ptr = sm_ctxt->get_diagnostic_tree (ptr);
if (diag_ptr)
sm_ctxt->warn
new file mode 100644
@@ -0,0 +1,27 @@
+/* Reproducer for false positive from -Wanalyzer-deref-before-check
+ seen on Linux kernel's block/bdev.c due to -fanalyzer mishandling
+ inlined functions. */
+
+/* { dg-additional-options "-O2 -g -fno-delete-null-pointer-checks" } */
+
+typedef unsigned char u8;
+struct inode {
+ void *i_mapping;
+ u8 i_blkbits;
+};
+struct block_device {
+ struct inode *bd_inode;
+};
+int sync_blockdev(struct block_device *bdev);
+int set_blocksize(struct block_device *bdev, u8 size) {
+ if (bdev->bd_inode->i_blkbits != size) { /* { dg-bogus "pointer 'bdev' is dereferenced here" } */
+ sync_blockdev(bdev);
+ }
+ return 0;
+}
+extern int filemap_write_and_wait(void *);
+int sync_blockdev(struct block_device *bdev) {
+ if (!bdev) /* { dg-bogus "check of 'bdev' for NULL after already dereferencing it" } */
+ return 0;
+ return filemap_write_and_wait(bdev->bd_inode->i_mapping);
+}