Sms

How buffer overflow in SMS response buffer handling happens in C and how to fix it

A critical buffer overflow vulnerability was discovered in `sm_at_sms.c`, where three consecutive unsafe string operations — `sprintf()`, `strcpy()`, and `strcat()` — wrote SMS payload data into a fixed-size buffer without any bounds checking. An attacker capable of crafting an oversized SMS message could overflow `sms_ctx.concat_rsp_buf`, corrupting adjacent stack or heap memory. The fix replaces all three unsafe calls with their bounds-aware counterparts: `snprintf()` and `strcat_s()`.