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Pointers smear memory protection #1243

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Pointers smear memory protection #1243

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a46461c
Add smear memory protection to pointers when evaluating them in a boo…
gcmoreira Aug 25, 2024
305eeda
Use only boolean context to identify invalid pointers
gcmoreira Aug 25, 2024
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10 changes: 10 additions & 0 deletions volatility3/framework/objects/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -445,6 +445,16 @@ def is_readable(self, layer_name: Optional[str] = None) -> bool:
layer_name = layer_name or self.vol.native_layer_name
return self._context.layers[layer_name].is_valid(self, self.vol.subtype.size)

def __bool__(self):
"""Enables checking if a pointer is valid in its memory layer when its evaluated
in a boolean context, for instance:
if not ptr:
continue
Without this method, the code above will only abort if 'ptr = 0', leaving the
code vulnerable to smear memory.
"""
return self.is_readable()

def __getattr__(self, attr: str) -> Any:
"""Convenience function to access unknown attributes by getting them
from the subtype object."""
Expand Down
14 changes: 5 additions & 9 deletions volatility3/framework/plugins/linux/pidhashtable.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ class PIDHashTable(plugins.PluginInterface):

_required_framework_version = (2, 0, 0)

_version = (1, 0, 0)
_version = (1, 0, 1)

@classmethod
def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
Expand All @@ -45,9 +45,7 @@ def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]
]

def _is_valid_task(self, task) -> bool:
vmlinux = self.context.modules[self.config["kernel"]]
vmlinux_layer = self.context.layers[vmlinux.layer_name]
return bool(task and task.pid > 0 and vmlinux_layer.is_valid(task.parent))
return bool(task and task.pid > 0 and task.parent)

def _get_pidtype_pid(self):
vmlinux = self.context.modules[self.config["kernel"]]
Expand Down Expand Up @@ -88,15 +86,14 @@ def _get_pidhash_array(self):

def _walk_upid(self, seen_upids, upid):
vmlinux = self.context.modules[self.config["kernel"]]
vmlinux_layer = self.context.layers[vmlinux.layer_name]

while upid and vmlinux_layer.is_valid(upid.vol.offset):
while upid:
if upid.vol.offset in seen_upids:
break
seen_upids.add(upid.vol.offset)

pid_chain = upid.pid_chain
if not (pid_chain and vmlinux_layer.is_valid(pid_chain.vol.offset)):
if not pid_chain:
break

upid = linux.LinuxUtilities.container_of(
Expand All @@ -105,7 +102,6 @@ def _walk_upid(self, seen_upids, upid):

def _get_upids(self):
vmlinux = self.context.modules[self.config["kernel"]]
vmlinux_layer = self.context.layers[vmlinux.layer_name]

# 2.6.24 <= kernels < 4.15
pidhash = self._get_pidhash_array()
Expand All @@ -115,7 +111,7 @@ def _get_upids(self):
# each entry in the hlist is a upid which is wrapped in a pid
ent = hlist.first

while ent and vmlinux_layer.is_valid(ent.vol.offset):
while ent:
# upid->pid_chain exists 2.6.24 <= kernel < 4.15
upid = linux.LinuxUtilities.container_of(
ent.vol.offset, "upid", "pid_chain", vmlinux
Expand Down
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