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ELF unexec: align section header

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This ports the recent unexelf.c changes to Fedora x86-64
when configured with GCC’s -fsanitize=undefined option.
* src/unexelf.c (unexec): Align new_data2_size to a multiple
of ElfW (Shdr)’s alignment, so that NEW_SECTION_H returns a
pointer aligned appropriately for its type.
This commit is contained in:
Paul Eggert 2015-11-16 17:48:08 -08:00
parent 1cdddc1db6
commit c9fd597a4c
1 changed files with 8 additions and 3 deletions
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11
src/unexelf.c
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@ -247,7 +247,7 @@ unexec (const char *new_name, const char *old_name)
ElfW (Phdr) *old_bss_seg, *new_bss_seg;
ElfW (Addr) old_bss_addr, new_bss_addr;
ElfW (Word) old_bss_size, new_data2_size;
ElfW (Word) old_bss_size, bss_size_growth, new_data2_size;
ElfW (Off) old_bss_offset, new_data2_offset;
ptrdiff_t n;
@ -331,7 +331,11 @@ unexec (const char *new_name, const char *old_name)
new_break = sbrk (0);
new_bss_addr = (ElfW (Addr)) new_break;
new_data2_size = new_bss_addr - old_bss_addr;
bss_size_growth = new_bss_addr - old_bss_addr;
new_data2_size = bss_size_growth;
new_data2_size += alignof (ElfW (Shdr)) - 1;
new_data2_size -= new_data2_size % alignof (ElfW (Shdr));
new_data2_offset = old_bss_offset;
#ifdef UNEXELF_DEBUG
@ -399,7 +403,8 @@ unexec (const char *new_name, const char *old_name)
new_bss_seg->p_memsz = new_bss_seg->p_filesz;
/* Copy over what we have in memory now for the bss area. */
memcpy (new_base + new_data2_offset, (caddr_t) old_bss_addr, new_data2_size);
memcpy (new_base + new_data2_offset, (caddr_t) old_bss_addr,
bss_size_growth);
/* Walk through all section headers, copying data and updating. */
for (n = 1; n < old_file_h->e_shnum; n++)