c0f4a8a7fc
The fast path for string literals fails to consider the offset of the pointer into an array of chars, this change simply adds the required checks and bounds corrections prior to calling strnlen. Fixes #173175
38 lines
1.8 KiB
C
38 lines
1.8 KiB
C
// RUN: %clang_cc1 -std=c23 -triple x86_64 -verify -fsyntax-only -Wfortify-source -Wno-string-plus-int %s
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// RUN: %clang_cc1 -std=c23 -triple x86_64 -verify -fsyntax-only -Wfortify-source -Wno-string-plus-int -fexperimental-new-constant-interpreter %s
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void test(char *c) {
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// We test offsets 0 to 4.
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// 0: a no op of course
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// 1,2: these result in a different length string than the buffer size
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// 3: the last position: this hits ptr+object_size being a valid pointer,
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// but not dereferencable
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// 4: completely invalid pointer
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__builtin_strcat(c, "42" + 0);
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__builtin_strcat(c, "42" + 1);
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__builtin_strcat(c, "42" + 2);
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__builtin_strcat(c, "42" + 3);
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__builtin_strcat(c, "42" + 4);
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_Static_assert(__builtin_strlen("42" + 0) == 2);
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// A test without a null terminator, this captures incorrect size computation
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// and incorrectly specifying the buffer size to strlen.
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char buffer[1];
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static const char test_buffer[] = {'4','2'};
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__builtin_strcpy(buffer, test_buffer + 0);
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__builtin_strcpy(buffer, test_buffer + 1);
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// Note: these show that we will not issue a fortify warning when the source
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// buffer is not null terminated.
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__builtin_strcpy(buffer, test_buffer + 2);
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__builtin_strcpy(buffer, test_buffer + 3);
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// Verifying strlen computes from the correct starting point.
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_Static_assert(__builtin_strlen("42" + 1) == 1);
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_Static_assert(__builtin_strlen("42" + 2) == 0);
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_Static_assert(__builtin_strlen("42" + 3));
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// expected-error@-1 {{static assertion expression is not an integral constant expression}}
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_Static_assert(__builtin_strlen("42" + 4));
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// expected-error@-1 {{static assertion expression is not an integral constant expression}}
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// expected-note@-2 {{cannot refer to element 4 of array of 3 elements in a constant expression}}
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}
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