elf_reader: only read data from PROGBITS sections, ignore NOBITS #740
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'Virtual' NOBITS sections like .bss always share an offset with another ELF section, but reading from them is expected to yield only NUL bytes. Prior to Go 1.18, opening a NOBITS section would yield a reader into the overlapping 'real' section, dutifully returning its non-NUL bytes and potentially reading past the end of the underlying file reader if the size of the NOBITS section was large enough. This was addressed in CL#375216. As both an optimization (in case of large .bss sections) and a workaround for this bug in Go versions 1.17 and earlier, only read data from PROGBITS sections, which all known LLVM versions use correctly. Return an error if a data section is not PROGBITS or NOBITS. Signed-off-by: Timo Beckers <timo@isovalent.com>
rgo3
approved these changes
Jul 20, 2022
lmb
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Jul 20, 2022
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'Virtual' NOBITS sections like .bss always share an offset with another ELF section, but reading from them is expected to yield only NUL bytes.
Prior to Go 1.18, opening a NOBITS section would yield a reader into the overlapping 'real' section, dutifully returning its non-NUL bytes and potentially reading past the end of the underlying file reader if the size of the NOBITS section was large enough. This was addressed in CL#375216.
As both an optimization (in case of large .bss sections) and a workaround for this bug in Go versions 1.17 and earlier, only read data from PROGBITS sections, which all known LLVM versions use correctly. Return an error if a data section is not PROGBITS or NOBITS.
Addresses #668 (comment).