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Avoid bug in ld-linux to set brk(0) when .p_align is large.

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modified:   p_lx_elf.cpp
This commit is contained in:
John Reiser 2016-10-03 09:41:05 -07:00
parent 870cdfa51f
commit e3fe0dc89b
1 changed files with 11 additions and 1 deletions
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12
src/p_lx_elf.cpp
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@ -2286,7 +2286,17 @@ PackLinuxElf64::generateElfHdr(
// linux-2.6.14 binfmt_elf.c: SIGKILL if (0==.p_memsz) on a page boundary
unsigned const brkb = brka | ((0==(~page_mask & brka)) ? 0x20 : 0);
set_te32(&h2->phdr[1].p_type, PT_LOAD64); // be sure
set_te64(&h2->phdr[1].p_offset, ~page_mask & brkb);
// Invoking by ld-linux-x86_64-2.21 complains if (filesize < .p_offset),
// which can happen with good compression of a stripped executable
// and large .p_align. However (0==.p_filesz) so ld-linux has a bug.
// Try to evade the bug by reducing .p_align. The alignment is forced
// anyway by phdr[0].p_align and constant offset from phdr[0].p_vaddr.
// However, somebody might complain because (.p_vaddr - .p_offset)
// is divisible only by phdr[1].p_align, and not by phdr[0].p_align.
set_te64(&h2->phdr[1].p_align, 0x1000);
set_te64(&h2->phdr[1].p_offset, /*~page_mask*/ 0xfff & brkb);
set_te64(&h2->phdr[1].p_vaddr, brkb);
set_te64(&h2->phdr[1].p_paddr, brkb);
h2->phdr[1].p_filesz = 0;