CVE-2020-27795: 
NixOS vulnerability analysis and mitigation

A segmentation fault vulnerability was discovered in radare2 with the adf command (CVE-2020-27795). The issue exists in libr/core/cmdanal.c, where when the 'adf' command is used with no or wrong arguments, the analfcndata function returns a null pointer for fcn, causing a segmentation fault in ensurefcn_range function. This vulnerability affects versions up to (excluding) 4.4.0 (NVD).

The vulnerability occurs in the analfcndata function within libr/core/cmdanal.c. When executing the adf command without proper arguments, the function ranalgetfcnin(core->anal, core->offset, -1) returns a null pointer, which later causes a segmentation fault in ensurefcn_range(fcn). The vulnerability has been assigned a CVSS v3.1 Base Score of 7.5 HIGH with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (NVD).

When exploited, this vulnerability leads to a segmentation fault, causing the application to crash. This results in a denial of service condition, affecting the availability of the radare2 system (NVD).

The vulnerability was fixed in radare2 version 4.4.0. The fix involves modifying the ranalgetfcnin function call to include RANALFCNTYPEANY as a parameter instead of -1, and restructuring the code to handle the fcn_size calculation after validating that fcn is not null (GitHub Patch).