readelf: Allocate job_data one-by-one as needed

Currently, job_data is stored in an array whose size is equal to the
number of debug sections (.debug_*, .eh_frame, .gdb_index, etc.).

This size may be too small if a binary contains multiple debug sections
with the same name.  For example an ET_REL binary compiled with -ggdb3
can contain multiple .debug_macro sections.

Fix this by allocating job_data on the fly when preparing to read a
debug section.  This supports an arbitrary number of debug sections
while also avoiding unnecessary memory allocation.

https://sourceware.org/bugzilla/show_bug.cgi?id=33580

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

diff --git a/src/readelf.c b/src/readelf.c
index ee6c203d0acc2f1353a714067dad347f639efcb3..a2d1735873cfdaf24ce712cbb912af4dd586ca00 100644 (file)
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -12200,7 +12200,8 @@ getone_dwflmod (Dwfl_Module *dwflmod,
   return DWARF_CB_OK;
 }
 
-typedef struct {
+typedef struct Job_Data {
+  struct Job_Data *next;
   Dwfl_Module *dwflmod;
   Ebl *ebl;
   GElf_Ehdr *ehdr;
@@ -12230,7 +12231,7 @@ do_job (void *data, FILE *out)
    If thread safety is not supported or the maximum number of threads is set
    to 1, then immediately call START_ROUTINE with the given arguments.  */
 static void
-schedule_job (job_data jdata[], size_t idx,
+schedule_job (job_data **jdatalist,
              void (*start_routine) (Dwfl_Module *, Ebl *, GElf_Ehdr *,
                                     Elf_Scn *, GElf_Shdr *, Dwarf *, FILE *),
              Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr, Elf_Scn *scn,
@@ -12239,21 +12240,24 @@ schedule_job (job_data jdata[], size_t idx,
 #ifdef USE_LOCKS
   if (max_threads > 1)
     {
-      /* Add to the job queue.  */
-      jdata[idx].dwflmod = dwflmod;
-      jdata[idx].ebl = ebl;
-      jdata[idx].ehdr = ehdr;
-      jdata[idx].scn = *scn;
-      jdata[idx].shdr = *shdr;
-      jdata[idx].dbg = dbg;
-      jdata[idx].fp = start_routine;
+      job_data *jdata = xmalloc (sizeof (job_data));
+
+      jdata->dwflmod = dwflmod;
+      jdata->ebl = ebl;
+      jdata->ehdr = ehdr;
+      jdata->scn = *scn;
+      jdata->shdr = *shdr;
+      jdata->dbg = dbg;
+      jdata->fp = start_routine;
+      jdata->next = *jdatalist;
+      *jdatalist = jdata;
 
-      add_job (do_job, (void *) &jdata[idx]);
+      add_job (do_job, (void *) jdata);
     }
   else
     start_routine (dwflmod, ebl, ehdr, scn, shdr, dbg, stdout);
 #else
-  (void) jdata; (void) idx;
+  (void) jdatalist;
 
   start_routine (dwflmod, ebl, ehdr, scn, shdr, dbg, stdout);
 #endif
@@ -12431,8 +12435,7 @@ print_debug (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr)
   if (unlikely (elf_getshdrstrndx (ebl->elf, &shstrndx) < 0))
     error_exit (0, _("cannot get section header string table index"));
 
-  ssize_t num_jobs = 0;
-  job_data *jdata = NULL;
+  job_data *jdatalist = NULL;
 
   /* If the .debug_info section is listed as implicitly required then
      we must make sure to handle it before handling any other debug
@@ -12531,13 +12534,6 @@ print_debug (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr)
          if (name == NULL)
            continue;
 
-         if (jdata == NULL)
-           {
-             jdata = calloc (ndebug_sections, sizeof (*jdata));
-             if (jdata == NULL)
-               error_exit (0, _("failed to allocate job data"));
-           }
-
          int n;
          for (n = 0; n < ndebug_sections; ++n)
            {
@@ -12561,10 +12557,9 @@ print_debug (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr)
                {
                  if (((print_debug_sections | implicit_debug_sections)
                       & debug_sections[n].bitmask))
-                   schedule_job (jdata, num_jobs++, debug_sections[n].fp,
+                   schedule_job (&jdatalist, debug_sections[n].fp,
                                  dwflmod, ebl, ehdr, scn, shdr, dbg);
 
-                 assert (num_jobs <= ndebug_sections);
                  break;
                }
            }
@@ -12579,7 +12574,13 @@ print_debug (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr)
 
   dwfl_end (skel_dwfl);
   free (skel_name);
-  free (jdata);
+
+  while (jdatalist != NULL)
+    {
+      job_data *jdata = jdatalist;
+      jdatalist = jdatalist->next;
+      free (jdata);
+    }
 
   /* Turn implicit and/or explicit back on in case we go over another file.  */
   if (implicit_info)