From 0b3f6f7f182f3363fc499e52b27649e05c1ad381 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 16 Nov 2015 17:48:08 -0800 Subject: [PATCH] ELF unexec: align section header MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. --- src/unexelf.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/src/unexelf.c b/src/unexelf.c index c10c7f2..03e6daf 100644 --- a/src/unexelf.c +++ b/src/unexelf.c @@ -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++) -- 2.1.0