Safer sections iteration #29
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assafnativ
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+1 for this |
aclements
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Jul 29, 2020
| @@ -103,8 +103,14 @@ elf::elf(const std::shared_ptr<loader> &l) | |||
| // Load sections | |||
| const void *sec_data = l->load(m->hdr.shoff, | |||
| m->hdr.shentsize * m->hdr.shnum); | |||
| if (NULL == sec_data) { | |||
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loader.load is not allowed to return NULL (it's supposed to throw an exception if there's a problem) and the mmap loader implementation doesn't return NULL, so I'm afraid I don't understand what this change is accomplishing.
| for (unsigned i = 0; i < m->hdr.shnum; i++) { | ||
| const void *sec = ((const char*)sec_data) + i * m->hdr.shentsize; | ||
| if (NULL == sec) { |
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It doesn't make sense for sec to be NULL here, since it's a result from a pointer offset from sec_data. In practice the only way this can happen is if sec_data itself is NULL, but then we shouldn't have even done the pointer arithmetic.
| @@ -103,8 +103,14 @@ elf::elf(const std::shared_ptr<loader> &l) | |||
| // Load sections | |||
| const void *sec_data = l->load(m->hdr.shoff, | |||
| m->hdr.shentsize * m->hdr.shnum); | |||
| if (NULL == sec_data) { | |||
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Please follow the coding conventions of the surrounding code, which uses forward comparison: sec_data == NULL.
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File with the hash of ee4b726d2601b084e02f4fb7411a26054fa8a1053f011d3ee9d5a422d93f342c was crashing this parser.