[binutils-gdb] PR32260: Improve error handling on string merging

[Michael Matz]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ed3228de9b3335e5c97f738fc22d682f56d42316

commit ed3228de9b3335e5c97f738fc22d682f56d42316
Author: Michael Matz <matz@suse.de>
Date:   Tue Oct 15 18:47:15 2024 +0200

    PR32260: Improve error handling on string merging
    
    if the input sections are near the max supported size (4G)
    we might fail to enlarge the hash table.  The error handling
    for this case didn't quite work.  When this happens we can
    gracefully fall back to just not deduplicate this section
    (and continue with further mergable sections).  We were mixing
    that with the case of not being able to even allocate a small
    structure (in which case we can as well error out completely),
    this disentables both cases.
    
            bfd/
    
            PR ld/32260
            * merge.c (sec_merge_maybe_resize): Check overflow in ultimate
            target type.
            (record_section): Return three-state, use new state when unable
            to enlarge hash table.
            (_bfd_merge_sections): Remove current section from merging
            consideration when hashtable can't be enlarged.

Diff:
---
 bfd/merge.c | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/bfd/merge.c b/bfd/merge.c
index 5c8e69bedd9..c811bc57eae 100644
--- a/bfd/merge.c
+++ b/bfd/merge.c
@@ -165,7 +165,7 @@ struct sec_merge_sec_info
 
 /* Given a merge hash table TABLE and a number of entries to be
    ADDED, possibly resize the table for this to fit without further
-   resizing.  */
+   resizing.  Returns false if that can't be done for whatever reason.  */
 
 static bool
 sec_merge_maybe_resize (struct sec_merge_hash *table, unsigned added)
@@ -174,17 +174,18 @@ sec_merge_maybe_resize (struct sec_merge_hash *table, unsigned added)
   if (NEEDS_RESIZE (bfdtab->count + added, table->nbuckets))
     {
       unsigned i;
-      unsigned long newnb = table->nbuckets * 2;
+      unsigned long newnb = table->nbuckets;
       struct sec_merge_hash_entry **newv;
       uint64_t *newl;
       unsigned long alloc;
 
-      while (NEEDS_RESIZE (bfdtab->count + added, newnb))
+      do
 	{
 	  newnb *= 2;
-	  if (!newnb)
+	  if (!(unsigned int)newnb)
 	    return false;
 	}
+      while (NEEDS_RESIZE (bfdtab->count + added, newnb));
 
       alloc = newnb * sizeof (newl[0]);
       if (alloc / sizeof (newl[0]) != newnb)
@@ -698,9 +699,12 @@ _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 }
 
 /* Record one whole input section (described by SECINFO) into the hash table
-   SINFO.  */
+   SINFO.  Returns 0 on hard errors (no sense in continuing link),
+   1 when section is completely recorded, and 2 when the section wasn't
+   recorded but we can continue (e.g. by simply not deduplicating this
+   section).  */
 
-static bool
+static int
 record_section (struct sec_merge_info *sinfo,
 		struct sec_merge_sec_info *secinfo)
 {
@@ -737,8 +741,8 @@ record_section (struct sec_merge_info *sinfo,
      merged into this area will make use of that as well.  */
   if (!sec_merge_maybe_resize (sinfo->htab, 1 + sec->size / 2))
     {
-      bfd_set_error (bfd_error_no_memory);
-      goto error_return;
+      free (contents);
+      return 2;
     }
 
   /* Walk through the contents, calculate hashes and length of all
@@ -788,14 +792,14 @@ record_section (struct sec_merge_info *sinfo,
   /*printf ("ZZZ %s:%s %u entries\n", sec->owner->filename, sec->name,
 	  (unsigned)secinfo->noffsetmap);*/
 
-  return true;
+  return 1;
 
  error_return:
   free (contents);
   contents = NULL;
   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
     *secinfo->psecinfo = NULL;
-  return false;
+  return 0;
 }
 
 /* qsort comparison function.  Won't ever return zero as all entries
@@ -991,9 +995,16 @@ _bfd_merge_sections (bfd *abfd,
 	  }
 	else
 	  {
-	    if (!record_section (sinfo, secinfo))
+	    int e = record_section (sinfo, secinfo);
+	    if (e == 0)
 	      return false;
-	    if (align)
+	    if (e == 2)
+	      {
+		*secinfo->psecinfo = NULL;
+		if (remove_hook)
+		  (*remove_hook) (abfd, secinfo->sec);
+	      }
+	    else if (align)
 	      {
 		unsigned int opb = bfd_octets_per_byte (abfd, secinfo->sec);
 
@@ -1043,7 +1054,8 @@ _bfd_merge_sections (bfd *abfd,
       /* Finally remove all input sections which have not made it into
 	 the hash table at all.  */
       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
-	if (secinfo->first_str == NULL)
+	if (secinfo->first_str == NULL
+	    && secinfo->sec->sec_info_type == SEC_INFO_TYPE_MERGE)
 	  secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
     }