Patch libunwind manually to fix the access violation to unblock sourc…

…e build (dotnet#97813)
hwoodiwiss · Feb 1, 2024 · 5cd9eb8 · 5cd9eb8
1 parent 113af73
commit 5cd9eb8
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Showing 2 changed files with 14 additions and 8 deletions.
diff --git a/src/native/external/libunwind-version.txt b/src/native/external/libunwind-version.txt
@@ -6,3 +6,4 @@ Apply https://github.com/libunwind/libunwind/pull/701
 Apply https://github.com/libunwind/libunwind/pull/703
 Apply https://github.com/libunwind/libunwind/pull/704
 Revert https://github.com/libunwind/libunwind/pull/503 # issue: https://github.com/libunwind/libunwind/issues/702
+Apply https://github.com/libunwind/libunwind/pull/714
diff --git a/src/native/external/libunwind/src/dwarf/Gget_proc_info_in_range.c b/src/native/external/libunwind/src/dwarf/Gget_proc_info_in_range.c
@@ -58,26 +58,30 @@ unw_get_proc_info_in_range (unw_word_t        start_ip,
     if (eh_frame_table != 0) {
         unw_accessors_t *a = unw_get_accessors_int (as);
 
-        struct dwarf_eh_frame_hdr* exhdr = NULL;
-        if ((*a->access_mem)(as, eh_frame_table, (unw_word_t*)&exhdr, 0, arg) < 0) {
+        unw_word_t data;
+        if ((*a->access_mem)(as, eh_frame_table, &data, 0, arg) < 0) {
             return -UNW_EINVAL;
         }
+        /* we are reading only the first 4 `char` members of `struct dwarf_eh_frame_hdr`, which
+         * are guaranteed to fit into the first `sizeof(unw_word_t)` bytes */
+        struct dwarf_eh_frame_hdr exhdr;
+        memcpy(&exhdr, &data, sizeof(data));
 
-        if (exhdr->version != DW_EH_VERSION) {
-            Debug (1, "Unexpected version %d\n", exhdr->version);
+        if (exhdr.version != DW_EH_VERSION) {
+            Debug (1, "Unexpected version %d\n", exhdr.version);
             return -UNW_EBADVERSION;
         }
         unw_word_t addr = eh_frame_table + offsetof(struct dwarf_eh_frame_hdr, eh_frame);
         unw_word_t eh_frame_start;
         unw_word_t fde_count;
 
         /* read eh_frame_ptr */
-        if ((ret = dwarf_read_encoded_pointer(as, a, &addr, exhdr->eh_frame_ptr_enc, pi, &eh_frame_start, arg)) < 0) {
+        if ((ret = dwarf_read_encoded_pointer(as, a, &addr, exhdr.eh_frame_ptr_enc, pi, &eh_frame_start, arg)) < 0) {
             return ret;
         }
 
         /* read fde_count */
-        if ((ret = dwarf_read_encoded_pointer(as, a, &addr, exhdr->fde_count_enc, pi, &fde_count, arg)) < 0) {
+        if ((ret = dwarf_read_encoded_pointer(as, a, &addr, exhdr.fde_count_enc, pi, &fde_count, arg)) < 0) {
             return ret;
         }
 
@@ -87,8 +91,8 @@ unw_get_proc_info_in_range (unw_word_t        start_ip,
             return -UNW_ENOINFO;
         }
 
-        if (exhdr->table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4)) {
-            Debug (1, "Table encoding not supported %x\n", exhdr->table_enc);
+        if (exhdr.table_enc != (DW_EH_PE_datarel | DW_EH_PE_sdata4)) {
+            Debug (1, "Table encoding not supported %x\n", exhdr.table_enc);
             return -UNW_EINVAL;
         }
 
@@ -113,3 +117,4 @@ unw_get_proc_info_in_range (unw_word_t        start_ip,
     }
     return UNW_ESUCCESS;
 }
+