Author: Balazs Benics Date: 2024-09-12T17:06:52+02:00 New Revision: 2e30f8d114e1406b35dc63868a92f4279330251b
URL: https://github.com/llvm/llvm-project/commit/2e30f8d114e1406b35dc63868a92f4279330251b DIFF: https://github.com/llvm/llvm-project/commit/2e30f8d114e1406b35dc63868a92f4279330251b.diff LOG: [analyzer] Fix StreamChecker crash in fread modeling (#108393) In #93408 https://github.com/llvm/llvm-project/commit/69bc159142c6e4ed168e32a6168392d396f891de I refined how invalidation is done for `fread`. It can crash, if the "size" or "count" parameters of "fread" is a perfectly constrained negative value. In such cases, when it will try to allocate a SmallVector with a negative size, which will cause a crash. To mitigate this issue, let's just guard against negative values. CPP-3247 Added: Modified: clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp clang/test/Analysis/fread.c Removed: ################################################################################ diff --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp index 22061373c4b393..8bb7880a3cc283 100644 --- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp +++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp @@ -1129,7 +1129,7 @@ tryToInvalidateFReadBufferByElements(ProgramStateRef State, CheckerContext &C, if (!ElemTy.isNull() && CountVal && Size && StartIndexVal) { int64_t NumBytesRead = Size.value() * CountVal.value(); int64_t ElemSizeInChars = Ctx.getTypeSizeInChars(ElemTy).getQuantity(); - if (ElemSizeInChars == 0) + if (ElemSizeInChars == 0 || NumBytesRead < 0) return nullptr; bool IncompleteLastElement = (NumBytesRead % ElemSizeInChars) != 0; diff --git a/clang/test/Analysis/fread.c b/clang/test/Analysis/fread.c index 3f286421fd7a13..5dc6c0c744093a 100644 --- a/clang/test/Analysis/fread.c +++ b/clang/test/Analysis/fread.c @@ -443,3 +443,33 @@ void test_unaligned_start_read(void) { fclose(fp); } } + +void no_crash_if_count_is_negative(long l, long r, unsigned char *buffer) { + FILE *fp = fopen("path", "r"); + if (fp) { + if (l * r == -1) { + fread(buffer, 1, l * r, fp); // no-crash + } + fclose(fp); + } +} + +void no_crash_if_size_is_negative(long l, long r, unsigned char *buffer) { + FILE *fp = fopen("path", "r"); + if (fp) { + if (l * r == -1) { + fread(buffer, l * r, 1, fp); // no-crash + } + fclose(fp); + } +} + +void no_crash_if_size_and_count_are_negative(long l, long r, unsigned char *buffer) { + FILE *fp = fopen("path", "r"); + if (fp) { + if (l * r == -1) { + fread(buffer, l * r, l * r, fp); // no-crash + } + fclose(fp); + } +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
