Crash in visual assembler on Windows due to incorrect rbuf URI parsing

[fietensen]

Environment

The current date is: 17/02/2025

radare2 5.9.8 1 @ windows-x86-64
birth: git.5.9.8 Tue 11/19/2024__11:46:03.42
commit: 4eb49d5ad8c99eaecc8850a2f10bad407067c898
options: gpl -O? cs:5 cl:1 meson

CYGWIN_NT-10.0-26100 x86_64

also tested on latest:
birth: git.5.9.8-366-gf7c3e892cf 17/02/2025__15:25:06,51
commit: f7c3e892cf21e8e91f62fde2d2ce36fbd30e0a5b
options: gpl -O? cs:5 cl:2 meson

Description

Radare2 crashes without notice when starting the visual assembler from visual mode on Windows.

Issue Breakdown:

1. Trigger:
   • Starting visual assembler calls r_core_cmd_strf in vasm.c#L98.
2. Buffer Construction:
   • A RBuffer is created from the hex input in cmd.c#L5023-L5054.
3. Problematic URI Construction (in io.c#L54 using r_str_newf):
   • Linux: Generates valid URI: rbuf://0xdeadbeef.
   • Windows: Omits the 0xprefix, producing rbuf://DEADBEEF.
4. Faulty Address Parsing (in io_rbuf.c#L40 with r_num_get):
   • Linux: r_num_get(NULL, "0xdeadbeef") correctly parses 0xdeadbeef $\rightarrow$ 3735928559.
   • Windows: r_num_get(NULL, "DEADBEEF") misinterprets it, returning 0, causing an access violation.

Expected Behavior:

• The rbuf:// schema should be consistent across platforms.
• On Windows, the URI should retain the 0x prefix (rbuf://0xdeadbeef)
• This will ensure that r_num_get correctly decodes the address, preventing crashes

Test

Steps To Reproduce

1. Open Radare2 on Windows (radare2 -w -).
2. Enter visual mode with V.
3. Start the visual assembler (A).
4. Radare2 crashes immediately.