Rich Felker
149d872970
this corrects missing validation when using alternate group database backends via nscd, as reported by 0rbitingZer0, which could result in a heap-based buffer overflow. while the source of truth for user (passwd) and group definitions is generally an equal or higher-privilege domain than the application, and compromise of nscd could inherently lead to bypass of some access controls, it is still worthwhile to harden against direct attacks from a compromised nscd. this patch adds validation in the least invasive way possible, erroring out at the point where a write past the end of the buffer would previously have occurred. a check is also added for member counts that would cause arithmetic overflow in the existing buffer size computations, including negative counts. this could be handled better by making adjustments where the arithmetic is performed, but the way it's done here avoids making any changes except for the actual bounds check.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/