CVE-2024-38440: Off-by-one Error

Netatalk before 3.2.1 has an off-by-one error, and resultant heap-based buffer overflow and segmentation violation, because of incorrectly using FPLoginExt in BN_bin2bn in etc/uams/uams_dhx_pam.c. The original issue 1097 report stated: 'The latest version of Netatalk (v3.2.0) contains a security vulnerability. This vulnerability arises due to a lack of validation for the length field after parsing user-provided data, leading to an out-of-bounds heap write of one byte (\0). Under specific configurations, this can result in reading metadata of the next heap block, potentially causing a Denial of Service (DoS) under certain heap layouts or with ASAN enabled. ... The vulnerability is located in the FPLoginExt operation of Netatalk, in the BN_bin2bn function found in /etc/uams/uams_dhx_pam.c ... if (!(bn = BN_bin2bn((unsigned char *)ibuf, KEYSIZE, NULL))) ... threads ... [#0] Id 1, Name: "afpd", stopped 0x7ffff4304e58 in ?? (), reason: SIGSEGV ... [#0] 0x7ffff4304e58 mov BYTE PTR [r14+0x8], 0x0 ... mov rdx, QWORD PTR [rsp+0x18] ... afp_login_ext(obj=<optimized out>, ibuf=0x62d000010424 "", ibuflen=0xffffffffffff0015, rbuf=<optimized out>, rbuflen=<optimized out>) ... afp_over_dsi(obj=0x5555556154c0 <obj>).' 2.4.1 and 3.1.19 are also fixed versions.