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mm/zone: fix poison handling

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Loïc Grégoire
2026-10-26 14:41:21 -04:00
parent 7aaad602ea
commit b59947011b
1 changed files with 14 additions and 18 deletions
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src/sys/mm/zone.zig
+13 -17
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@@ -430,17 +430,17 @@ pub const Page = extern struct {
slab: *Slab, slab: *Slab,
}; };
inline fn fill_with_poison(ptr: *anyopaque, len: usize, pattern: u32) void { fn fill_with_poison(ptr: *anyopaque, len: usize, pattern: u32) void {
const bytes: [*]u8 = @ptrCast(ptr); const bytes: [*]u8 = @ptrCast(ptr);
var i: usize = 0; var i: usize = 0;
while (i + 4 <= len) : (i += 4) { while (i + 4 <= len) : (i += 4) {
std.mem.writeInt(u32, bytes[i..][0..4], pattern, .little); std.mem.writeInt(u32, bytes[i..][0..4], pattern, .native);
} }
if (i < len) { if (i < len) {
var tail: [4]u8 = undefined; var tail: [4]u8 = undefined;
std.mem.writeInt(u32, &tail, pattern, .little); std.mem.writeInt(u32, &tail, pattern, .native);
var j: usize = 0; var j: usize = 0;
while (i < len) : ({ while (i < len) : ({
i += 1; i += 1;
@@ -449,20 +449,21 @@ inline fn fill_with_poison(ptr: *anyopaque, len: usize, pattern: u32) void {
} }
} }
inline fn check_poison(ptr: *anyopaque, len: usize, pattern: u32) bool { fn check_poison(ptr: *anyopaque, len: usize, pattern: u32) bool {
if (!should_check_poison) return true; if (!should_check_poison) return true;
const bytes: [*]const u8 = @ptrCast(ptr); const bytes: [*]const u8 = @ptrCast(ptr);
var i: usize = 0; var i: usize = 0;
while (i + 4 <= len) : (i += 4) { while (i + 4 <= len) : (i += 4) {
if (std.mem.readInt(u32, bytes[i..][0..4], .little) != pattern) if (std.mem.readInt(u32, bytes[i..][0..4], .native) != pattern) {
return false; return false;
} }
}
if (i < len) { if (i < len) {
var tail: [4]u8 = undefined; var tail: [4]u8 = undefined;
std.mem.writeInt(u32, &tail, pattern, .little); std.mem.writeInt(u32, &tail, pattern, .native);
var j: usize = 0; var j: usize = 0;
while (i < len) : ({ while (i < len) : ({
i += 1; i += 1;
@@ -684,7 +685,10 @@ pub const Zone = struct {
if (is_poison_enabled and !self.flags.dont_touch) { if (is_poison_enabled and !self.flags.dont_touch) {
if (!check_poison(buf, self.obj_size, free_poison)) { if (!check_poison(buf, self.obj_size, free_poison)) {
@panic("poison mismatch: possible use-after-free"); std.debug.panic(
"poison mismatch: possible UaF on {*}",
.{buf},
);
} }
fill_with_poison(buf, self.obj_size, alloc_poison); fill_with_poison(buf, self.obj_size, alloc_poison);
@@ -983,7 +987,6 @@ pub const Zone = struct {
} }
fn slab_free(self: *Zone, obj: *anyopaque, poison: bool) void { fn slab_free(self: *Zone, obj: *anyopaque, poison: bool) void {
if (!is_poison_enabled or poison and !self.flags.dont_touch) {
if (!is_poison_enabled or (poison and !self.flags.dont_touch)) { if (!is_poison_enabled or (poison and !self.flags.dont_touch)) {
if (self.dtor) |dtor| { if (self.dtor) |dtor| {
dtor(obj); dtor(obj);
@@ -1081,17 +1084,11 @@ pub const Zone = struct {
slab.link.remove(); slab.link.remove();
} }
if (is_poison_enabled) { if (!is_poison_enabled) {
if (!check_poison(buf, self.obj_size, free_poison)) {
@panic("poison mismatch: possible use-after-free");
}
fill_with_poison(buf, self.obj_size, alloc_poison);
}
if (self.ctor) |ctor| { if (self.ctor) |ctor| {
ctor(buf); ctor(buf);
} }
}
elems[i] = buf; elems[i] = buf;
i += 1; i += 1;
@@ -1860,7 +1857,6 @@ pub fn smr_domain_create(preempt: bool) !*ke.smr.Domain {
var dom: *ke.smr.Domain = try smr_zone.create(); var dom: *ke.smr.Domain = try smr_zone.create();
dom.cpus = @ptrCast(@alignCast(try smr_cpu_zone.alloc(.{}))); dom.cpus = @ptrCast(@alignCast(try smr_cpu_zone.alloc(.{})));
dom.init(preempt); dom.init(preempt);
return dom; return dom;
} }