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authorRich Felker <dalias@aerifal.cx>2018-06-26 12:15:13 -0400
committerRich Felker <dalias@aerifal.cx>2018-06-26 12:22:29 -0400
commit68a5a23abcb9649f05728db4cf50bb4498937855 (patch)
treee1c94879314637164723f9e7a9a01177a6bb1b25 /arch/mips/syscall_arch.h
parent38f2fa3d0207b8060302129c6464662751d4f2d3 (diff)
downloadmusl-68a5a23abcb9649f05728db4cf50bb4498937855.tar.gz
fix dynamic linker mapping/clearing bss in first/only LOAD segment
writable load segments can have size-in-memory larger than their size in the ELF file, representing bss or equivalent. the initial partial page has to be zero-filled, and additional anonymous pages have to be mapped such that accesses don't failt with SIGBUS. map_library skips redundant MAP_FIXED mapping of the initial (lowest-address) segment when processing LOAD segments since it was already mapped when reserving the virtual address range, but in doing so, inadvertently also skipped the code to fill/map bss. typical executable and library files have two or more LOAD segments, and the first one is text/rodata (non-writable) and thus has no bss, but it is syntactically valid for an ELF program/library to put its writable segment first, or to have only one segment (everything writable). the binutils bfd-based linker has been observed to create such programs in the presence of unusual sections or linker scripts. fix by moving only the mmap_fixed operation under the conditional rather than skipping the remainder of the loop body. add a check to avoid bss processing in the case where the segment is not writable; this should not happen, but if it does, the change would be a crashing regression without this check.
Diffstat (limited to 'arch/mips/syscall_arch.h')
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