libelf: Make sure elf_getdata_rawchunk returns aligned data.

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>

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 25f673db32f37cb0cf0b759416f120bb0b23178d..30017cd7a46672cd4ef5c20cb2f910aeb8f8f661 100644 (file)
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,11 @@
+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.
+
 2015-06-02  Mark Wielaard  <mjw@redhat.com>
 
        * elf_getdata.c (convert_data): Make sure source data is properly

diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c
index 1a4981efb0a28aca7d8fde8bd84b5d16ccd52a4b..770e035504053e6c6ec87aa2df99939d3fa4463c 100644 (file)
--- 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 63a9914fd2c601280d6a4ef26dcffe32e77f66d4..5cc11e7026ad73458baf7a6e84e1bdb2a38ac8fb 100644 (file)
--- 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)
     {