When the elf file is mmapped ehdr can still point to ehdr_mem if the address is unaligned. In such cases we do need to memcpy the ehdr back to the file. We shouldn't when ehdr already comes directly from the mmapped file, because that would cause an memcpy call with overlapping addresses (ehdr being copied directly over itself).
Signed-off-by: Mark Wielaard <[email protected]> --- libelf/ChangeLog | 5 +++++ libelf/elf32_updatefile.c | 2 +- 2 files changed, 6 insertions(+), 1 deletions(-) diff --git a/libelf/ChangeLog b/libelf/ChangeLog index a996ccf..148c945 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2013-11-08 Mark Wielaard <[email protected]> + + * elf32_updatefile.c (elfXX_updatemmap): Only memcpy ehdr when not + already directly mmapped. + 2013-11-05 Mark Wielaard <[email protected]> * elf32_updatefile.c (elfXX_updatefile): Copy all section headers diff --git a/libelf/elf32_updatefile.c b/libelf/elf32_updatefile.c index c4af9c0..b39e284 100644 --- a/libelf/elf32_updatefile.c +++ b/libelf/elf32_updatefile.c @@ -133,7 +133,7 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum) (*fctp) ((char *) elf->map_address + elf->start_offset, ehdr, sizeof (ElfW2(LIBELFBITS,Ehdr)), 1); } - else + else if (elf->map_address + elf->start_offset != ehdr) memcpy (elf->map_address + elf->start_offset, ehdr, sizeof (ElfW2(LIBELFBITS,Ehdr))); -- 1.7.1
