RUSTSEC-2021-0119: Out-of-bounds write in nix::unistd::getgrouplist #39
Labels
cause::indirect dependency
This issue is caused/concerns a indirect dependency of GitArena (dependency of a dependency)
status::investigating
type::security
nix
0.20.0
^0.20.2,^0.21.2,^0.22.2,>=0.23.0
<0.16.0
On certain platforms, if a user has more than 16 groups, the
nix::unistd::getgrouplist
function will call the libcgetgrouplist
function with a length parameter greater than the size of the buffer it
provides, resulting in an out-of-bounds write and memory corruption.
The libc
getgrouplist
function takes an in/out parameterngroups
specifying the size of the group buffer. When the buffer is too small to
hold all of the reqested user's group memberships, some libc
implementations, including glibc and Solaris libc, will modify
ngroups
to indicate the actual number of groups for the user, in addition to
returning an error. The version of
nix::unistd::getgrouplist
in nix0.16.0 and up will resize the buffer to twice its size, but will not
read or modify the
ngroups
variable. Thus, if the user has more thantwice as many groups as the initial buffer size of 8, the next call to
getgrouplist
will then write past the end of the buffer.The issue would require editing /etc/groups to exploit, which is usually
only editable by the root user.
See advisory page for additional details.
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