[PATCH] libelf: Make sure elf_getdata_rawchunk returns aligned data.

[Mark Wielaard <mjw at redhat dot com>]

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 <mjw@redhat.com>
---
 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  <mjw@redhat.com>
 
+	* 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  <mjw@redhat.com>
+
 	* 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