elf_getdata_rawchunk might return an unaligned buffer for the requested ELF data type. Make sure the data is also correctly aligned when using an mmapped file. Also add some missing alignments for ELF data types for __libelf_type_align (the missing types could also make elf_getdata to return unaligned data).
Signed-off-by: Mark Wielaard <[email protected]> --- libelf/ChangeLog | 8 ++++++++ libelf/elf_getdata.c | 9 +++++++++ libelf/elf_getdata_rawchunk.c | 20 +++++++++++++++++--- 3 files changed, 34 insertions(+), 3 deletions(-) diff --git a/libelf/ChangeLog b/libelf/ChangeLog index a54a80b..c818400 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,5 +1,13 @@ 2015-06-04 Mark Wielaard <[email protected]> + * elf_getdata.c (__libelf_type_aligns): Add entries for ELF_T_EHDR, + ELF_T_OFF, ELF_T_PHDR, ELF_T_SHDR, ELF_T_SWORD, ELF_T_XWORD, + ELF_T_SXWORD, ELF_T_GNUHASH, ELF_T_AUXV. + * elf_getdata_rawchunk.c (elf_getdata_rawchunk): Check alignment + of rawdata against requested type. + +2015-06-04 Mark Wielaard <[email protected]> + * elf_begin.c (get_shnum): Check alignment of Shdr, not Ehdr before direct access. diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c index 1a4981e..770e035 100644 --- a/libelf/elf_getdata.c +++ b/libelf/elf_getdata.c @@ -83,8 +83,15 @@ const uint_fast8_t __libelf_type_aligns[EV_NUM - 1][ELFCLASSNUM - 1][ELF_T_NUM] # define TYPE_ALIGNS(Bits) \ { \ [ELF_T_ADDR] = __alignof__ (ElfW2(Bits,Addr)), \ + [ELF_T_EHDR] = __alignof__ (ElfW2(Bits,Ehdr)), \ [ELF_T_HALF] = __alignof__ (ElfW2(Bits,Half)), \ + [ELF_T_OFF] = __alignof__ (ElfW2(Bits,Off)), \ + [ELF_T_PHDR] = __alignof__ (ElfW2(Bits,Phdr)), \ + [ELF_T_SHDR] = __alignof__ (ElfW2(Bits,Shdr)), \ + [ELF_T_SWORD] = __alignof__ (ElfW2(Bits,Sword)), \ [ELF_T_WORD] = __alignof__ (ElfW2(Bits,Word)), \ + [ELF_T_XWORD] = __alignof__ (ElfW2(Bits,Xword)), \ + [ELF_T_SXWORD] = __alignof__ (ElfW2(Bits,Sxword)), \ [ELF_T_SYM] = __alignof__ (ElfW2(Bits,Sym)), \ [ELF_T_SYMINFO] = __alignof__ (ElfW2(Bits,Syminfo)), \ [ELF_T_REL] = __alignof__ (ElfW2(Bits,Rel)), \ @@ -97,6 +104,8 @@ const uint_fast8_t __libelf_type_aligns[EV_NUM - 1][ELFCLASSNUM - 1][ELF_T_NUM] [ELF_T_MOVE] = __alignof__ (ElfW2(Bits,Move)), \ [ELF_T_LIB] = __alignof__ (ElfW2(Bits,Lib)), \ [ELF_T_NHDR] = __alignof__ (ElfW2(Bits,Nhdr)), \ + [ELF_T_GNUHASH] = __alignof__ (Elf32_Word), \ + [ELF_T_AUXV] = __alignof__ (ElfW2(Bits,auxv_t)), \ } [EV_CURRENT - 1] = { diff --git a/libelf/elf_getdata_rawchunk.c b/libelf/elf_getdata_rawchunk.c index 63a9914..5cc11e7 100644 --- a/libelf/elf_getdata_rawchunk.c +++ b/libelf/elf_getdata_rawchunk.c @@ -79,9 +79,24 @@ elf_getdata_rawchunk (elf, offset, size, type) rwlock_rdlock (elf->lock); - /* If the file is mmap'ed we can use it directly. */ + size_t align = __libelf_type_align (elf->class, type); if (elf->map_address != NULL) - rawchunk = elf->map_address + elf->start_offset + offset; + { + /* If the file is mmap'ed we can use it directly, if aligned for type. */ + char *rawdata = elf->map_address + elf->start_offset + offset; + if (ALLOW_UNALIGNED || + ((uintptr_t) rawdata & (align - 1)) == 0) + rawchunk = rawdata; + else + { + /* We allocate the memory and memcpy it to get aligned data. */ + rawchunk = malloc (size); + if (rawchunk == NULL) + goto nomem; + memcpy (rawchunk, rawdata, size); + flags = ELF_F_MALLOCED; + } + } else { /* We allocate the memory and read the data from the file. */ @@ -108,7 +123,6 @@ elf_getdata_rawchunk (elf, offset, size, type) } /* Copy and/or convert the data as needed for aligned native-order access. */ - size_t align = __libelf_type_align (elf->class, type); void *buffer; if (elf->state.elf32.ehdr->e_ident[EI_DATA] == MY_ELFDATA) { -- 1.8.3.1
