elflint: Do not raise an error when note type is unrecognized

check_note_data compares the type of a given ELF note to a list of known
types.  If the type is not recognized then an "unknown note" error is
raised.

Unknown note types do not necessarily indicate a gABI/psABI compliance
issue so an error should not be raised for this reason alone.
Additionally some common note types are missing from the list of known
types (NT_FILE for example).

Fix this by removing the "unknown note" error from check_note_data.

This patch preserves existing type-specific format checks and adds a
check for the presence of the null terminator in the note name, if
applicable.  If one of these checks fails, a "malformed note" or
"missing null terminator" error is raised.

Since there are currently no type-specific checks for any ET_CORE
notes, these checks are only performed when the given binary does not
have e_type ET_CORE.

https://sourceware.org/bugzilla/show_bug.cgi?id=33488

Signed-off-by: Aaron Merey <amerey@redhat.com>

diff --git a/src/elflint.c b/src/elflint.c
index a46682c757ea0e152801a73bfdedc273966dd4be..daa9410d20d9d02d8a5aaa41584cf3b3ed7969a1 100644 (file)
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -4368,41 +4368,47 @@ check_note_data (Ebl *ebl, const GElf_Ehdr *ehdr,
     {
       last_offset = offset;
 
-      /* Make sure it is one of the note types we know about.  */
-      if (ehdr->e_type == ET_CORE)
-       switch (nhdr.n_type)
-         {
-         case NT_PRSTATUS:
-         case NT_FPREGSET:
-         case NT_PRPSINFO:
-         case NT_TASKSTRUCT:           /* NT_PRXREG on Solaris.  */
-         case NT_PLATFORM:
-         case NT_AUXV:
-         case NT_GWINDOWS:
-         case NT_ASRS:
-         case NT_PSTATUS:
-         case NT_PSINFO:
-         case NT_PRCRED:
-         case NT_UTSNAME:
-         case NT_LWPSTATUS:
-         case NT_LWPSINFO:
-         case NT_PRFPXREG:
-           /* Known type.  */
-           break;
+      /* gelf_getnote verified that this note is aligned and does not extend
+        outside of DATA.  Now check that the note name is null-terminated
+        if present.  */
+      if (name_offset != 0
+         && nhdr.n_namesz > 0
+         && *((char *) data->d_buf + name_offset + nhdr.n_namesz - 1) != '\0')
+       {
+         if (ehdr->e_type == ET_CORE)
+           {
+             if (shndx == 0)
+               ERROR (_("\
+phdr[%d]: name missing null terminator for core file note with type %" PRIu32
+                           " at offset %" PRIu64 "\n"),
+                      phndx, (uint32_t) nhdr.n_type, start + offset);
+             else
+               ERROR (_("\
+section [%2d] '%s': name missing null terminator for core file note with "
+                           "type %" PRIu32 " at offset %zu\n"),
+                      shndx, section_name (ebl, shndx),
+                      (uint32_t) nhdr.n_type, offset);
+           }
+         else
+           {
+             if (shndx == 0)
+               ERROR (_("\
+phdr[%d]: name missing null terminator for object file note with type %" PRIu32
+                           " at offset %zu\n"),
+                      phndx, (uint32_t) nhdr.n_type, offset);
+             else
+               ERROR (_("\
+section [%2d] '%s': name missing null terminator for object file note with "
+                           "type %" PRIu32 " at offset %zu\n"),
+                      shndx, section_name (ebl, shndx),
+                      (uint32_t) nhdr.n_type, offset);
+           }
 
-         default:
-           if (shndx == 0)
-             ERROR (_("\
-phdr[%d]: unknown core file note type %" PRIu32 " at offset %" PRIu64 "\n"),
-                    phndx, (uint32_t) nhdr.n_type, start + offset);
-           else
-             ERROR (_("\
-section [%2d] '%s': unknown core file note type %" PRIu32
-                             " at offset %zu\n"),
-                    shndx, section_name (ebl, shndx),
-                    (uint32_t) nhdr.n_type, offset);
-         }
-      else
+         continue;
+       }
+
+      /* Perform type-specific checks.  */
+      if (ehdr->e_type != ET_CORE)
        switch (nhdr.n_type)
          {
          case NT_GNU_ABI_TAG:
@@ -4412,15 +4418,15 @@ section [%2d] '%s': unknown core file note type %" PRIu32
          case NT_GNU_PROPERTY_TYPE_0:
            if (nhdr.n_namesz == sizeof ELF_NOTE_GNU
                && strcmp (data->d_buf + name_offset, ELF_NOTE_GNU) == 0)
-             break;
+             continue;
            else
              {
                /* NT_VERSION is 1, same as NT_GNU_ABI_TAG.  It has no
                   descriptor and (ab)uses the name as version string.  */
                if (nhdr.n_descsz == 0 && nhdr.n_type == NT_VERSION)
-                 break;
+                 continue;
              }
-             goto unknown_note;
+             goto malformed_note;
 
          case NT_GNU_BUILD_ATTRIBUTE_OPEN:
          case NT_GNU_BUILD_ATTRIBUTE_FUNC:
@@ -4431,39 +4437,43 @@ section [%2d] '%s': unknown core file note type %" PRIu32
                && strncmp (data->d_buf + name_offset,
                            ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX,
                            strlen (ELF_NOTE_GNU_BUILD_ATTRIBUTE_PREFIX)) == 0)
-             break;
+             continue;
            else
-             goto unknown_note;
+             goto malformed_note;
 
          case NT_FDO_PACKAGING_METADATA:
            if (nhdr.n_namesz == sizeof ELF_NOTE_FDO
                && strcmp (data->d_buf + name_offset, ELF_NOTE_FDO) == 0)
-             break;
+             continue;
            else
-             goto unknown_note;
+             goto malformed_note;
 
          case 0:
            /* Linux vDSOs use a type 0 note for the kernel version word.  */
            if (nhdr.n_namesz == sizeof "Linux"
                && !memcmp (data->d_buf + name_offset, "Linux", sizeof "Linux"))
-             break;
-           FALLTHROUGH;
+             continue;
+           else
+             goto malformed_note;
          default:
-           {
-           unknown_note:
+           /* n_type not recognized, but no errors found regarding alignment,
+              overflow or name null terminator.  */
+           continue;
+
+malformed_note:
            if (shndx == 0)
              ERROR (_("\
-phdr[%d]: unknown object file note type %" PRIu32 " with owner name '%s' at offset %zu\n"),
+phdr[%d]: malformed object file note type %" PRIu32 " with owner name '%s' "
+                             "at offset %zu\n"),
                     phndx, (uint32_t) nhdr.n_type,
                     (char *) data->d_buf + name_offset, offset);
            else
              ERROR (_("\
-section [%2d] '%s': unknown object file note type %" PRIu32
+section [%2d] '%s': malformed object file note type %" PRIu32
                              " with owner name '%s' at offset %zu\n"),
                     shndx, section_name (ebl, shndx),
                     (uint32_t) nhdr.n_type,
                     (char *) data->d_buf + name_offset, offset);
-           }
          }
     }