[PATCH] riscv: Allocate enough space to strcpy() string

[Christoph Müllner]

I triggered an ICE on Ubuntu 24.04 when compiling code that uses
function attributes. Looking into the sources shows that we have
a systematic issue in the attribute handling code:
* we determine the length with strlen() (excluding the terminating null)
* we allocate a buffer with this length
* we copy the original string using strcpy() (incl. the terminating null)

To quote the man page of strcpy():
"The programmer is responsible for allocating a  destination  buffer
large  enough,  that  is, strlen(src)  + 1."

The ICE looks like this:

*** buffer overflow detected ***: terminated
xtheadmempair_bench.c:14:1: internal compiler error: Aborted
   14 | {
      | ^
0xaf3b99 crash_signal
        /home/ubuntu/src/gcc/scaleff/gcc/toplev.cc:319
0xe5b957 strcpy
        /usr/include/riscv64-linux-gnu/bits/string_fortified.h:79
0xe5b957 riscv_process_target_attr
        /home/ubuntu/src/gcc/scaleff/gcc/config/riscv/riscv-target-attr.cc:339
0xe5baaf riscv_process_target_attr
        /home/ubuntu/src/gcc/scaleff/gcc/config/riscv/riscv-target-attr.cc:314
0xe5bc5f riscv_option_valid_attribute_p(tree_node*, tree_node*, tree_node*, int)
        /home/ubuntu/src/gcc/scaleff/gcc/config/riscv/riscv-target-attr.cc:389
0x6a31e5 handle_target_attribute
        /home/ubuntu/src/gcc/scaleff/gcc/c-family/c-attribs.cc:5915
0x5d3a07 decl_attributes(tree_node**, tree_node*, int, tree_node*)
        /home/ubuntu/src/gcc/scaleff/gcc/attribs.cc:900
0x5db403 c_decl_attributes
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-decl.cc:5501
0x5e8965 start_function(c_declspecs*, c_declarator*, tree_node*)
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-decl.cc:10562
0x6318ed c_parser_declaration_or_fndef
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-parser.cc:2914
0x63a8ad c_parser_external_declaration
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-parser.cc:2048
0x63b219 c_parser_translation_unit
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-parser.cc:1902
0x63b219 c_parse_file()
        /home/ubuntu/src/gcc/scaleff/gcc/c/c-parser.cc:27277
0x68fec5 c_common_parse_file()
        /home/ubuntu/src/gcc/scaleff/gcc/c-family/c-opts.cc:1311
Please submit a full bug report, with preprocessed source (by using 
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

gcc/ChangeLog:

        * config/riscv/riscv-target-attr.cc 
(riscv_target_attr_parser::parse_arch):
        Fix allocation size of buffer.
        (riscv_process_one_target_attr): Likewise.
        (riscv_process_target_attr): Likewise.

Signed-off-by: Christoph Müllner <christoph.muell...@vrull.eu>
---
 gcc/config/riscv/riscv-target-attr.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gcc/config/riscv/riscv-target-attr.cc 
b/gcc/config/riscv/riscv-target-attr.cc
index 1a73d69bf50..19eb7b06d54 100644
--- a/gcc/config/riscv/riscv-target-attr.cc
+++ b/gcc/config/riscv/riscv-target-attr.cc
@@ -109,7 +109,7 @@ riscv_target_attr_parser::parse_arch (const char *str)
     {
       /* Parsing the extension list like "+<ext>[,+<ext>]*".  */
       size_t len = strlen (str);
-      std::unique_ptr<char[]> buf (new char[len]);
+      std::unique_ptr<char[]> buf (new char[len+1]);
       char *str_to_check = buf.get ();
       strcpy (str_to_check, str);
       const char *token = strtok_r (str_to_check, ",", &str_to_check);
@@ -247,7 +247,7 @@ riscv_process_one_target_attr (char *arg_str,
       return false;
     }
 
-  std::unique_ptr<char[]> buf (new char[len]);
+  std::unique_ptr<char[]> buf (new char[len+1]);
   char *str_to_check = buf.get();
   strcpy (str_to_check, arg_str);
 
@@ -334,7 +334,7 @@ riscv_process_target_attr (tree fndecl, tree args, 
location_t loc,
       return false;
     }
 
-  std::unique_ptr<char[]> buf (new char[len]);
+  std::unique_ptr<char[]> buf (new char[len+1]);
   char *str_to_check = buf.get ();
   strcpy (str_to_check, TREE_STRING_POINTER (args));
 
-- 
2.45.1