libdwfl: Call xlatetom on aligned buffers in dwfl_link_map_report

Make sure that when calling xlatetom for Phdrs and Dyns in
dwfl_link_map_report the input buffer is correctly aligned by calling
memcpy and setting in.d_buf to out.d_buf.

https://sourceware.org/bugzilla/show_bug.cgi?id=28720

Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 49a35e4..73d8613 100644 (file)
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,10 @@
 2021-12-23  Mark Wielaard  <mark@klomp.org>
 
+       * link_map.c (dwfl_link_map_report): Call memcpy and set in.d_buf to
+       out.d_buf before calling xlatetom for unaligned buffers.
+
+2021-12-23  Mark Wielaard  <mark@klomp.org>
+
        * core-file.c (dwfl_elf_phdr_memory_callback): Check start <
        elf->maximum_size and end - start < minread.
 

diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
index c4f79f1..f57c558 100644 (file)
--- a/libdwfl/link_map.c
+++ b/libdwfl/link_map.c
@@ -922,11 +922,20 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
                      return false;
                    }
                }
+             bool is32 = (elfclass == ELFCLASS32);
+             size_t phdr_align = (is32
+                                  ? __alignof__ (Elf32_Phdr)
+                                  : __alignof__ (Elf64_Phdr));
+             if (!in_from_exec
+                 && ((uintptr_t) in.d_buf & (phdr_align - 1)) != 0)
+               {
+                 memcpy (out.d_buf, in.d_buf, in.d_size);
+                 in.d_buf = out.d_buf;
+               }
              if (likely ((elfclass == ELFCLASS32
                           ? elf32_xlatetom : elf64_xlatetom)
                          (&out, &in, elfdata) != NULL))
                {
-                 bool is32 = (elfclass == ELFCLASS32);
                  for (size_t i = 0; i < phnum; ++i)
                    {
                      GElf_Word type = (is32
@@ -1044,6 +1053,14 @@ dwfl_link_map_report (Dwfl *dwfl, const void *auxv, size_t auxv_size,
                };
              if (in.d_size > out.d_size)
                in.d_size = out.d_size;
+             size_t dyn_align = (elfclass == ELFCLASS32
+                                 ? __alignof__ (Elf32_Dyn)
+                                 : __alignof__ (Elf64_Dyn));
+             if (((uintptr_t) in.d_buf & (dyn_align - 1)) != 0)
+               {
+                 memcpy (out.d_buf, in.d_buf, in.d_size);
+                 in.d_buf = out.d_buf;
+               }
              if (likely ((elfclass == ELFCLASS32
                           ? elf32_xlatetom : elf64_xlatetom)
                          (&out, &in, elfdata) != NULL))