perm_read() bounds a permission value by SEL_VEC_MAX but never by the
nprim of the owning class or common, which is taken verbatim from the
policy image. security_get_permissions() then writes perms[value - 1]
into an nprim-sized kcalloc() array, so a class declaring fewer
permissions than its largest permission value drives an out-of-bounds
heap write. The top-level symbol tables are validated this way; the
nested per-class permission table is not.
Reject a permission whose value exceeds nprim, which is already set when
perm_read() runs. Well-formed policies are unaffected.
Cc: stable@vger.kernel.org
Fixes: 55fcf09b3f ("selinux: add support for querying object classes and permissions from the running policy")
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: tweak comment for line length]
Signed-off-by: Paul Moore <paul@paul-moore.com>
d14b5d0e97