[clang][analyzer] Relax assertion for non-default address spaces in the cstring checker

[nuudlman]

Prevent an assertion failure in the cstring checker when library functions like memcpy are defined with non-default address spaces.

Adds a test for this case.

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[llvmbot]

@llvm/pr-subscribers-clang-static-analyzer-1

Author: Isaac Nudelman (nuudlman)

Changes

Prevent an assertion failure in the cstring checker when library functions like memcpy are defined with non-default address spaces.

Adds a test for this case.

---

Full diff: https://github.com/llvm/llvm-project/pull/153498.diff

2 Files Affected:

• (modified) clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp (+3-3)
• (modified) clang/test/Analysis/element-region-address-space.c (+16-1)

diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
index 0e5fc0a074938..b16118e86c0c1 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -1129,9 +1129,9 @@ bool CStringChecker::isFirstBufInBound(CheckerContext &C, ProgramStateRef State,
   if (!ER)
     return true; // cf top comment.
 
-  // FIXME: Does this crash when a non-standard definition
-  // of a library function is encountered?
-  assert(ER->getValueType() == C.getASTContext().CharTy &&
+  // Support library functions defined with non-default address spaces
+  assert(ER->getValueType().getCanonicalType().getUnqualifiedType() ==
+             C.getASTContext().CharTy &&
          "isFirstBufInBound should only be called with char* ElementRegions");
 
   // Get the size of the array.
diff --git a/clang/test/Analysis/element-region-address-space.c b/clang/test/Analysis/element-region-address-space.c
index dd7066240fef6..6d657eeedca30 100644
--- a/clang/test/Analysis/element-region-address-space.c
+++ b/clang/test/Analysis/element-region-address-space.c
@@ -1,11 +1,26 @@
 // RUN: %clang_analyze_cc1 -triple amdgcn-unknown-unknown \
-// RUN:   -analyzer-checker=core -verify %s
+// RUN:   -analyzer-checker=core,unix -verify %s
 
 // expected-no-diagnostics
 //
 // By default, pointers are 64-bits.
+#define ADDRESS_SPACE_64BITS __attribute__((address_space(0)))
 #define ADDRESS_SPACE_32BITS __attribute__((address_space(3)))
 
 int test(ADDRESS_SPACE_32BITS int *p, ADDRESS_SPACE_32BITS void *q) {
   return p == q; // no-crash
 }
+
+// Make sure that the cstring checker handles non-default address spaces
+ADDRESS_SPACE_64BITS void *
+memcpy(ADDRESS_SPACE_64BITS void *,
+       ADDRESS_SPACE_32BITS const void *,
+       long unsigned int);
+
+typedef struct {
+  char m[1];
+} k;
+
+void l(ADDRESS_SPACE_32BITS char *p, ADDRESS_SPACE_64BITS k *n) {
+  memcpy(&n->m[0], p, 4);
+}
\ No newline at end of file

[llvmbot]

@llvm/pr-subscribers-clang

Author: Isaac Nudelman (nuudlman)

Changes

Prevent an assertion failure in the cstring checker when library functions like memcpy are defined with non-default address spaces.

Adds a test for this case.

---

Full diff: https://github.com/llvm/llvm-project/pull/153498.diff

2 Files Affected:

• (modified) clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp (+3-3)
• (modified) clang/test/Analysis/element-region-address-space.c (+16-1)

diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
index 0e5fc0a074938..b16118e86c0c1 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -1129,9 +1129,9 @@ bool CStringChecker::isFirstBufInBound(CheckerContext &C, ProgramStateRef State,
   if (!ER)
     return true; // cf top comment.
 
-  // FIXME: Does this crash when a non-standard definition
-  // of a library function is encountered?
-  assert(ER->getValueType() == C.getASTContext().CharTy &&
+  // Support library functions defined with non-default address spaces
+  assert(ER->getValueType().getCanonicalType().getUnqualifiedType() ==
+             C.getASTContext().CharTy &&
          "isFirstBufInBound should only be called with char* ElementRegions");
 
   // Get the size of the array.
diff --git a/clang/test/Analysis/element-region-address-space.c b/clang/test/Analysis/element-region-address-space.c
index dd7066240fef6..6d657eeedca30 100644
--- a/clang/test/Analysis/element-region-address-space.c
+++ b/clang/test/Analysis/element-region-address-space.c
@@ -1,11 +1,26 @@
 // RUN: %clang_analyze_cc1 -triple amdgcn-unknown-unknown \
-// RUN:   -analyzer-checker=core -verify %s
+// RUN:   -analyzer-checker=core,unix -verify %s
 
 // expected-no-diagnostics
 //
 // By default, pointers are 64-bits.
+#define ADDRESS_SPACE_64BITS __attribute__((address_space(0)))
 #define ADDRESS_SPACE_32BITS __attribute__((address_space(3)))
 
 int test(ADDRESS_SPACE_32BITS int *p, ADDRESS_SPACE_32BITS void *q) {
   return p == q; // no-crash
 }
+
+// Make sure that the cstring checker handles non-default address spaces
+ADDRESS_SPACE_64BITS void *
+memcpy(ADDRESS_SPACE_64BITS void *,
+       ADDRESS_SPACE_32BITS const void *,
+       long unsigned int);
+
+typedef struct {
+  char m[1];
+} k;
+
+void l(ADDRESS_SPACE_32BITS char *p, ADDRESS_SPACE_64BITS k *n) {
+  memcpy(&n->m[0], p, 4);
+}
\ No newline at end of file

[vabridgers]

LGTM, let's let @NagyDonat review, comment and approve. Thanks!

[NagyDonat]

Overall the commit looks good to me, but I added some minor technical suggestions in inline comments.

[NagyDonat]

Removing this FIXME seems to be justified -- I tried declaring memcpy in a wildly nonstandard variant (with int * pointers) and there was no crash.

(No action expected, just mentioning this for other reviewers.)

[nuudlman]

@NagyDonat or @vabridgers Can one of you activate the workflows?

[steakhal]

Thanks for the patch!
Do as you wish.

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