loongarch readelf support

[Vaseeharan Vinayagamoorthy]

I have observed the following build error:

binutils-gdb/binutils/readelf.c:14044:15: error: ‘value’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
         value -= reloc->r_addend + symtab[sym_index].st_value;
               ^
cc1: all warnings being treated as errors
make[3]: *** [Makefile:1932: readelf.o] Error 1


Build machine: x86_64-none-linux-gnu
For Host: x86_64-none-linux-gnu
Target: aarch64-none-elf / aarch64_be-none-elf / arm-none-eabi

Please let me know if you require any other information to help resolve this.
________________________________
From: Binutils <binutils-bounces+vvinayag=arm.com@sourceware.org> on behalf of Alan Modra via Binutils <binutils@sourceware.org>
Sent: 02 June 2023 01:00
To: binutils@sourceware.org <binutils@sourceware.org>
Subject: loongarch readelf support

This fixes two buffer overflows found by fuzzers.

        * readelf.c (target_specific_reloc_handling): Sanity check
        loongarch reloc symbol index.  Don't apply reloc after errors.
        Reduce translation work of "invalid symbol index" error message.

diff --git a/binutils/readelf.c b/binutils/readelf.c
index 7292dd0941a..042d2301517 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -14028,24 +14028,32 @@ target_specific_reloc_handling (Filedata *filedata,
                            "ULEB128 value\n"),
                          (long) reloc->r_offset);

-               if (107 == reloc_type)
-                 value += (reloc->r_addend + symtab[sym_index].st_value);
-               else if (108 == reloc_type)
-                 value -= (reloc->r_addend + symtab[sym_index].st_value);
-
-               /* Write uleb128 value to p.  */
-               bfd_byte c;
-               bfd_byte *p = start + reloc->r_offset;
-               do
+               else if (sym_index >= num_syms)
+                 error (_("%s reloc contains invalid symbol index "
+                          "%" PRIu64 "\n"),
+                        (reloc_type == 107
+                         ? "R_LARCH_ADD_ULEB128"
+                         : "R_LARCH_SUB_ULEB128"),
+                        sym_index);
+               else
                   {
-                   c = value & 0x7f;
-                   if (reloc_size > 1)
-                     c |= 0x80;
-                   *(p++) = c;
-                   value >>= 7;
-                   reloc_size--;
+                   if (reloc_type == 107)
+                     value += reloc->r_addend + symtab[sym_index].st_value;
+                   else
+                     value -= reloc->r_addend + symtab[sym_index].st_value;
+
+                   /* Write uleb128 value to p.  */
+                   bfd_byte *p = start + reloc->r_offset;
+                   do
+                     {
+                       bfd_byte c = value & 0x7f;
+                       value >>= 7;
+                       if (--reloc_size != 0)
+                         c |= 0x80;
+                       *p++ = c;
+                     }
+                   while (reloc_size);
                   }
-               while (reloc_size);

                 return true;
               }
@@ -14075,8 +14083,8 @@ target_specific_reloc_handling (Filedata *filedata,
           case 23: /* R_MSP430X_GNU_SUB_ULEB128 */
             /* PR 21139.  */
             if (sym_index >= num_syms)
-             error (_("MSP430 SYM_DIFF reloc contains invalid symbol index"
-                      " %" PRIu64 "\n"), sym_index);
+             error (_("%s reloc contains invalid symbol index "
+                      "%" PRIu64 "\n"), "MSP430 SYM_DIFF", sym_index);
             else
               saved_sym = symtab + sym_index;
             return true;
@@ -14126,9 +14134,8 @@ target_specific_reloc_handling (Filedata *filedata,
                            " contains invalid ULEB128 value\n"),
                          reloc->r_offset);
                 else if (sym_index >= num_syms)
-                 error (_("MSP430 reloc contains invalid symbol index "
-                          "%" PRIu64 "\n"),
-                        sym_index);
+                 error (_("%s reloc contains invalid symbol index "
+                          "%" PRIu64 "\n"), "MSP430", sym_index);
                 else
                   {
                     value = reloc->r_addend + (symtab[sym_index].st_value
@@ -14173,9 +14180,8 @@ target_specific_reloc_handling (Filedata *filedata,
             return true;
           case 33: /* R_MN10300_SYM_DIFF */
             if (sym_index >= num_syms)
-             error (_("MN10300_SYM_DIFF reloc contains invalid symbol index "
-                      "%" PRIu64 "\n"),
-                    sym_index);
+             error (_("%s reloc contains invalid symbol index "
+                      "%" PRIu64 "\n"), "MN10300_SYM_DIFF", sym_index);
             else
               saved_sym = symtab + sym_index;
             return true;
@@ -14188,9 +14194,8 @@ target_specific_reloc_handling (Filedata *filedata,
                 uint64_t value;

                 if (sym_index >= num_syms)
-                 error (_("MN10300 reloc contains invalid symbol index "
-                          "%" PRIu64 "\n"),
-                        sym_index);
+                 error (_("%s reloc contains invalid symbol index "
+                          "%" PRIu64 "\n"), "MN10300", sym_index);
                 else
                   {
                     value = reloc->r_addend + (symtab[sym_index].st_value
@@ -14233,8 +14238,8 @@ target_specific_reloc_handling (Filedata *filedata,
           case 0x80: /* R_RL78_SYM.  */
             saved_sym1 = saved_sym2;
             if (sym_index >= num_syms)
-             error (_("RL78_SYM reloc contains invalid symbol index "
-                      "%" PRIu64 "\n"), sym_index);
+             error (_("%s reloc contains invalid symbol index "
+                      "%" PRIu64 "\n"), "RL78_SYM", sym_index);
             else
               {
                 saved_sym2 = symtab[sym_index].st_value;

--
Alan Modra
Australia Development Lab, IBM