* [PATCH v8 1/6] of/overlay: look up absolute target-paths absolutely
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 2/6] of/overlay: return ERR_PTR from dup_and_fixup_symbol_prop() Abdurrahman Hussain
` (4 subsequent siblings)
5 siblings, 0 replies; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
find_target() with a non-NULL target base concatenates the base path
and the fragment's target-path via "%pOF%s": target-path="/foo"
resolves to "<base>/foo" and can never reach the DT root. An overlay
applied with a base cannot both extend the base subtree and add
/aliases entries, which is what a PCI device declaring its
peripherals under dev_of_node() needs for alias-based bus numbering.
Treat any non-empty target-path as absolute. An empty target-path
still means the base itself, the only form used by the one in-tree
caller passing a base (drivers/misc/lan966x_pci.c).
Spell the contract out in the kernel-doc for @base/@target_base and
in find_target()'s strategy comment.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
drivers/of/overlay.c | 38 ++++++++++++++++++--------------------
1 file changed, 18 insertions(+), 20 deletions(-)
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 83c56dd9b5d8..6f2d7872028a 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -692,12 +692,15 @@ static int build_changeset(struct overlay_changeset *ovcs)
*
* 1) "target" property containing the phandle of the target
* 2) "target-path" property containing the path of the target
+ *
+ * With a non-NULL @target_base, an empty "target-path" means
+ * @target_base itself; any non-empty "target-path" is resolved
+ * absolutely from the live-tree root.
*/
static struct device_node *find_target(const struct device_node *info_node,
const struct device_node *target_base)
{
struct device_node *node;
- char *target_path;
const char *path;
u32 val;
int ret;
@@ -713,23 +716,14 @@ static struct device_node *find_target(const struct device_node *info_node,
ret = of_property_read_string(info_node, "target-path", &path);
if (!ret) {
- if (target_base) {
- target_path = kasprintf(GFP_KERNEL, "%pOF%s", target_base, path);
- if (!target_path)
- return NULL;
- node = of_find_node_by_path(target_path);
- if (!node) {
- pr_err("find target, node: %pOF, path '%s' not found\n",
- info_node, target_path);
- }
- kfree(target_path);
- } else {
- node = of_find_node_by_path(path);
- if (!node) {
- pr_err("find target, node: %pOF, path '%s' not found\n",
- info_node, path);
- }
- }
+ /* an empty target-path means the target base itself */
+ if (target_base && path[0] == '\0')
+ return of_node_get((struct device_node *)target_base);
+
+ node = of_find_node_by_path(path);
+ if (!node)
+ pr_err("find target, node: %pOF, path '%s' not found\n",
+ info_node, path);
return node;
}
@@ -741,7 +735,9 @@ static struct device_node *find_target(const struct device_node *info_node,
/**
* init_overlay_changeset() - initialize overlay changeset from overlay tree
* @ovcs: Overlay changeset to build
- * @target_base: Point to the target node to apply overlay
+ * @target_base: Target for fragments with an empty "target-path";
+ * fragments with a non-empty "target-path" resolve
+ * absolutely and ignore @target_base
*
* Initialize @ovcs. Populate @ovcs->fragments with node information from
* the top level of @overlay_root. The relevant top level nodes are the
@@ -991,7 +987,9 @@ static int of_overlay_apply(struct overlay_changeset *ovcs,
* @overlay_fdt: pointer to overlay FDT
* @overlay_fdt_size: number of bytes in @overlay_fdt
* @ret_ovcs_id: pointer for returning created changeset id
- * @base: pointer for the target node to apply overlay
+ * @base: target for fragments with an empty "target-path";
+ * fragments with a non-empty "target-path" resolve
+ * absolutely and ignore @base
*
* Creates and applies an overlay changeset.
*
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v8 2/6] of/overlay: return ERR_PTR from dup_and_fixup_symbol_prop()
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 1/6] of/overlay: look up absolute target-paths absolutely Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 3/6] of: hold a reference on of_aliases during alias path resolution Abdurrahman Hussain
` (3 subsequent siblings)
5 siblings, 0 replies; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
dup_and_fixup_symbol_prop() returns NULL for malformed values, for
values that are not paths into one of the overlay's fragments, and
for allocation failures. The caller reports all of them as -ENOMEM,
so a structural problem in /__symbols__ is diagnosed as memory
exhaustion.
A later patch reuses the helper for /aliases values and must handle
the three cases differently: copy verbatim, warn, or fail the apply.
Return ERR_PTR(-EINVAL), ERR_PTR(-ENODEV) and ERR_PTR(-ENOMEM)
respectively and propagate the errno in the /__symbols__ caller.
Also verify that the value descends through the matched fragment's
__overlay__ node before cutting the prefix. Only the first path
component was resolved, so an absolute live-tree value sharing its
first component with a fragment name was sliced at the prefix length
and rewritten to garbage. A prefix mismatch returns -ENODEV.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
drivers/of/overlay.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 6f2d7872028a..bc0c879dd807 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -206,6 +206,10 @@ static void overlay_fw_devlink_refresh(struct overlay_changeset *ovcs)
* The duplicated property value will be modified by replacing the
* "/fragment_name/__overlay/" portion of the value with the target
* path from the fragment node.
+ *
+ * Return: the fixed-up property, or ERR_PTR: -EINVAL if @prop's value
+ * is not a valid non-empty C string, -ENODEV if it is not a path into
+ * one of @ovcs's fragments, -ENOMEM on allocation failure.
*/
static struct property *dup_and_fixup_symbol_prop(
struct overlay_changeset *ovcs, const struct property *prop)
@@ -217,6 +221,8 @@ static struct property *dup_and_fixup_symbol_prop(
const char *path;
const char *path_tail;
const char *target_path;
+ char *overlay_name;
+ bool mismatch;
int k;
int overlay_name_len;
int path_len;
@@ -224,14 +230,14 @@ static struct property *dup_and_fixup_symbol_prop(
int target_path_len;
if (!prop->value)
- return NULL;
+ return ERR_PTR(-EINVAL);
if (strnlen(prop->value, prop->length) >= prop->length)
- return NULL;
+ return ERR_PTR(-EINVAL);
path = prop->value;
path_len = strlen(path);
if (path_len < 1)
- return NULL;
+ return ERR_PTR(-EINVAL);
fragment_node = __of_find_node_by_path(ovcs->overlay_root, path + 1);
overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
of_node_put(fragment_node);
@@ -243,18 +249,27 @@ static struct property *dup_and_fixup_symbol_prop(
break;
}
if (k >= ovcs->count)
- return NULL;
+ return ERR_PTR(-ENODEV);
+
+ overlay_name = kasprintf(GFP_KERNEL, "%pOF", fragment->overlay);
+ if (!overlay_name)
+ return ERR_PTR(-ENOMEM);
+ overlay_name_len = strlen(overlay_name);
- overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
+ /* @path must descend through this fragment's __overlay__ node */
+ mismatch = overlay_name_len > path_len ||
+ strncmp(path, overlay_name, overlay_name_len) != 0 ||
+ (path[overlay_name_len] != '/' && path[overlay_name_len]);
+ kfree(overlay_name);
+ if (mismatch)
+ return ERR_PTR(-ENODEV);
- if (overlay_name_len > path_len)
- return NULL;
path_tail = path + overlay_name_len;
path_tail_len = strlen(path_tail);
target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
if (!target_path)
- return NULL;
+ return ERR_PTR(-ENOMEM);
target_path_len = strlen(target_path);
/* a root target renders as "/"; drop it to avoid "//" results */
if (target_path_len == 1 && target_path[0] == '/' && path_tail_len)
@@ -284,7 +299,7 @@ static struct property *dup_and_fixup_symbol_prop(
err_free_target_path:
kfree(target_path);
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
/**
@@ -353,6 +368,8 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
if (prop)
return -EINVAL;
new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
+ if (IS_ERR(new_prop))
+ return PTR_ERR(new_prop);
} else {
new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
}
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v8 3/6] of: hold a reference on of_aliases during alias path resolution
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 1/6] of/overlay: look up absolute target-paths absolutely Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 2/6] of/overlay: return ERR_PTR from dup_and_fixup_symbol_prop() Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
2026-10-14 23:32 ` sashiko-bot
2026-10-14 23:17 ` [PATCH v8 4/6] of: update /aliases lookup on reconfig notifications Abdurrahman Hussain
` (2 subsequent siblings)
5 siblings, 1 reply; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
of_find_node_opts_by_path() walks the property list of of_aliases
without taking a reference on the node and passes pp->value straight
to of_find_node_by_path().
Take a reference across the walk. The walk itself stays lock-free
like every other property iteration: it can race property surgery and
see a stale view (a removed property's ->next is repointed at the
deadprops list), but nothing it can reach is freed while the node
reference is held. The pointer load itself needs no locking:
of_aliases always holds a reference on the node it points to, so a
reader that observes a non-NULL pointer observes a live node. A later
patch in this series clears of_aliases and drops that reference when
the node is detached at runtime; the detach path holds its own
references across the transition.
Validate the value before resolving it. of_alias_value_ok() requires
a non-empty, NUL-terminated, absolute path:
- an empty property has a NULL value and crashes in strchr()
- a value without a NUL inside the property is read past its end
- a relative value naming another alias (loop = "loop") recurses
through of_find_node_by_path() until the stack is exhausted
All three are reachable with a malformed boot FDT today.
The name comparison loses its redundant strlen() pass while here.
Fixes: c22e650e66b8 ("of: Make of_find_node_by_path() handle /aliases")
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
drivers/of/base.c | 17 ++++++++++++-----
drivers/of/of_private.h | 8 ++++++++
2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 57313055d9ed..6a6d9f8439dd 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1003,6 +1003,8 @@ struct device_node *of_find_node_opts_by_path(const char *path, const char **opt
/* The path could begin with an alias */
if (*path != '/') {
+ struct device_node *aliases;
+ const char *value = NULL;
int len;
const char *p = strchrnul(path, '/');
@@ -1010,16 +1012,21 @@ struct device_node *of_find_node_opts_by_path(const char *path, const char **opt
p = separator;
len = p - path;
- /* of_aliases must not be NULL */
- if (!of_aliases)
+ aliases = of_node_get(of_aliases);
+ if (!aliases)
return NULL;
- for_each_property_of_node(of_aliases, pp) {
- if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
- np = of_find_node_by_path(pp->value);
+ for_each_property_of_node(aliases, pp) {
+ if (!strncmp(pp->name, path, len) && !pp->name[len]) {
+ if (of_alias_value_ok(pp))
+ value = pp->value;
break;
}
}
+ /* the reference on @aliases keeps @value alive */
+ if (value)
+ np = of_find_node_by_path(value);
+ of_node_put(aliases);
if (!np)
return NULL;
path = p;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 0ae16da066e2..9bba999f0bf8 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -215,6 +215,14 @@ static inline bool is_pseudo_property(const char *prop_name)
!of_prop_cmp(prop_name, "linux,phandle");
}
+/* alias values must be absolute paths NUL-terminated within length */
+static inline bool of_alias_value_ok(const struct property *pp)
+{
+ return pp->value && pp->length >= 2 &&
+ *(const char *)pp->value == '/' &&
+ strnlen(pp->value, pp->length) < pp->length;
+}
+
#if IS_ENABLED(CONFIG_KUNIT)
int __of_address_resource_bounds(struct resource *r, u64 start, u64 size);
#endif
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH v8 3/6] of: hold a reference on of_aliases during alias path resolution
2026-10-14 23:17 ` [PATCH v8 3/6] of: hold a reference on of_aliases during alias path resolution Abdurrahman Hussain
@ 2026-10-14 23:32 ` sashiko-bot
0 siblings, 0 replies; 10+ messages in thread
From: sashiko-bot @ 2026-10-14 23:32 UTC (permalink / raw)
To: Abdurrahman Hussain; +Cc: devicetree, robh, conor+dt
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] of: lockless TOCTOU UAF reading of_aliases against concurrent overlay detach
--
commit 66550105e7f11866d2d8f8f454161df1bb855fa8
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>
of: hold a reference on of_aliases during alias path resolution
This commit takes a reference across the walk of the of_aliases property
list in of_find_node_opts_by_path() to prevent accessing stale views. It
also validates the alias value before resolving it to avoid crashes on
malformed boot FDTs.
> The pointer load itself needs no locking:
> of_aliases always holds a reference on the node it points to, so a
> reader that observes a non-NULL pointer observes a live node. A later
> patch in this series clears of_aliases and drops that reference when
> the node is detached at runtime; the detach path holds its own
> references across the transition.
[Severity: High]
Is this description accurate regarding the lack of locking for the pointer
load?
While the detach path holds a reference during the transition, if
of_changeset_destroy() runs immediately after the revert without any RCU
grace period, it could drop the final reference to the node.
Since of_node_release() uses kfree() and not kfree_rcu(), the object is
destroyed immediately, which leaves a race window open.
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 57313055d9ede..6a6d9f8439dd1 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
[ ... ]
> @@ -1010,16 +1012,21 @@ struct device_node *of_find_node_opts_by_path(const char *path, const char **opt
> p = separator;
> len = p - path;
>
> - /* of_aliases must not be NULL */
> - if (!of_aliases)
> + aliases = of_node_get(of_aliases);
[Severity: High]
Can this lockless read lead to a TOCTOU race and a use-after-free?
If a thread calls of_find_node_opts_by_path() and reads the global of_aliases
pointer, but gets preempted before taking the reference in of_node_get():
Thread 1
of_find_node_opts_by_path()
aliases = of_aliases;
<preempted>
Thread 2 could concurrently remove an overlay containing a dynamically
created /aliases node. The detach notifier clears of_aliases = NULL and
drops its reference, and then of_changeset_destroy() drops the final
reference to the node, freeing it synchronously via kfree().
When Thread 1 resumes:
Thread 1
of_node_get(aliases);
Could this lead to dereferencing node->kobj on freed memory?
Should this read be protected by devtree_lock or similar synchronization to
prevent the node from being freed before the reference is taken?
> + if (!aliases)
> return NULL;
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-nh-of-alias-overlay-v8-0-0f74f05ac762@nexthop.ai?part=3
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v8 4/6] of: update /aliases lookup on reconfig notifications
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
` (2 preceding siblings ...)
2026-10-14 23:17 ` [PATCH v8 3/6] of: hold a reference on of_aliases during alias path resolution Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
2026-10-14 23:29 ` sashiko-bot
2026-10-14 23:17 ` [PATCH v8 5/6] of/overlay: rewrite /aliases path values to live-tree paths Abdurrahman Hussain
2026-10-14 23:17 ` [PATCH v8 6/6] of: unittest: cover /aliases updates from overlay apply/revert Abdurrahman Hussain
5 siblings, 1 reply; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
Aliases added by overlays never make it into aliases_lookup, which is
only filled by of_alias_scan() at boot. of_alias_get_id() returns
-ENODEV for them and drivers using alias based numbering (i2c, spi,
tty, mmc) fall back to dynamic ids.
Register a reconfig notifier and mirror /aliases property changes
into aliases_lookup. The notifier chain covers changesets and
overlays, so no overlay specific hook is needed. Same approach as
Geert's 2015 series [1], which was never reposted;
of_alias_create()/of_alias_destroy() keep its names.
The /aliases node is matched by name and root parent instead of the
of_aliases pointer, which is still NULL when an overlay creates the
node on a system without a boot-time /aliases. The name match is
exact, of_node_name_eq() would also match "aliases@1". ATTACH stores
the node in of_aliases with a reference held, DETACH drops it again
and flushes aliases_lookup. The reference makes the lock-free
of_node_get(of_aliases) in of_find_node_opts_by_path() safe: a reader
that observes a non-NULL pointer observes a live node, and on DETACH
the changeset holds its own references across the notifier so the put
here cannot be the final one while readers still walk the node.
Nodes attached with properties already set are not scanned, as
before.
Lookup entries are created by of_alias_scan()'s old loop body, moved
into of_alias_create(). Entries created at runtime have kstrdup'ed
names and an of_node_get'ed target and are flagged "owned" so
of_alias_destroy() knows what to kfree(); boot entries live in
memblock and are only unlinked. Removal matches entries regardless of
ownership so updating a boot-time alias does not leave duplicates
behind, which was Grant's main concern on the old series [2].
A new aliases_mutex protects the list. of_mutex does not work here:
the notifier runs under it on the overlay path but outside of it on
the of_add_property() path.
of_alias_create() skips names that are empty or all digits instead of
creating an entry with an empty stem.
Only built for CONFIG_OF_DYNAMIC: there are no notifications without
it and the register stub returns -EINVAL.
Document the result in overlay-notes.rst, in particular that an overlay
alias naming an id a subsystem has already handed out dynamically now
makes that device's registration fail with -EBUSY rather than silently
falling back to a dynamic id.
Link: https://lore.kernel.org/lkml/1435675876-2159-1-git-send-email-geert+renesas@glider.be/ [1]
Link: https://lore.kernel.org/lkml/20150630172131.D4E6CC4041A@trevor.secretlab.ca/ [2]
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
Documentation/devicetree/overlay-notes.rst | 16 +++
drivers/of/base.c | 199 +++++++++++++++++++++++------
drivers/of/device.c | 4 +-
drivers/of/of_private.h | 14 ++
4 files changed, 191 insertions(+), 42 deletions(-)
diff --git a/Documentation/devicetree/overlay-notes.rst b/Documentation/devicetree/overlay-notes.rst
index ba401ef850e7..1ba1770e2c16 100644
--- a/Documentation/devicetree/overlay-notes.rst
+++ b/Documentation/devicetree/overlay-notes.rst
@@ -148,3 +148,19 @@ pointers to the overlay nodes or data. Any example of an inadvertent use
of such pointers is if a driver or subsystem module is loaded after an
overlay has been applied, and the driver or subsystem scans the entire
devicetree or a large portion of it, including the overlay nodes.
+
+Overlays and /aliases
+---------------------
+
+An overlay may add entries to /aliases. They are mirrored into the kernel's
+alias lookup as the overlay is applied, so of_alias_get_id() honors them just
+like the aliases present at boot, and removing the overlay removes them again.
+
+An alias is a request for one specific id, not a hint. Subsystems hand out
+ids dynamically to devices that have no alias, and they cannot reserve ids for
+an overlay that has not been loaded yet, so an overlay alias may name an id
+that is already in use. When that happens the device registration fails
+instead of silently falling back to a dynamic id: i2c_add_adapter() and
+spi_register_controller() return -EBUSY, and a serial port fails to be added.
+Choose overlay alias indices above anything the base system allocates
+dynamically.
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 6a6d9f8439dd..b70dedce06fe 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1934,6 +1934,159 @@ static void of_alias_add(struct alias_prop *ap, struct device_node *np,
ap->alias, ap->stem, ap->id, np);
}
+/*
+ * Protects aliases_lookup and of_aliases. of_alias_scan() runs single-
+ * threaded at init and skips it; every other reader/writer must hold it.
+ */
+DEFINE_MUTEX(aliases_mutex);
+
+/* Callers other than of_alias_scan() must hold @aliases_mutex. */
+static void of_alias_create(const struct property *pp,
+ void *(*dt_alloc)(u64 size, u64 align),
+ bool owned)
+{
+ const char *start = pp->name;
+ const char *end;
+ struct device_node *np;
+ struct alias_prop *ap;
+ const char *dup;
+ int id, len;
+
+ if (is_pseudo_property(pp->name))
+ return;
+
+ if (!of_alias_value_ok(pp))
+ return;
+
+ np = of_find_node_by_path(pp->value);
+ if (!np)
+ return;
+
+ end = start + strlen(start);
+ while (end > start && isdigit(*(end - 1)))
+ end--;
+ len = end - start;
+ if (len == 0)
+ goto out_put;
+
+ if (kstrtoint(end, 10, &id) < 0)
+ goto out_put;
+
+ ap = dt_alloc(sizeof(*ap) + len + 1, __alignof__(*ap));
+ if (!ap)
+ goto out_put;
+ memset(ap, 0, sizeof(*ap) + len + 1);
+
+ if (owned) {
+ dup = kstrdup(pp->name, GFP_KERNEL);
+ if (!dup) {
+ kfree(ap);
+ goto out_put;
+ }
+ } else {
+ dup = start;
+ }
+ ap->alias = dup;
+ ap->owned = owned;
+ of_alias_add(ap, np, id, start, len);
+ return;
+
+out_put:
+ of_node_put(np);
+}
+
+#ifdef CONFIG_OF_DYNAMIC
+/* Unlink @ap; free its storage if it was runtime-allocated. */
+static void __of_alias_del(struct alias_prop *ap)
+{
+ list_del(&ap->link);
+ of_node_put(ap->np);
+ if (ap->owned) {
+ kfree(ap->alias);
+ kfree(ap);
+ }
+}
+
+/* Callers must hold @aliases_mutex. */
+static void of_alias_destroy(const char *name)
+{
+ struct alias_prop *ap, *tmp;
+
+ list_for_each_entry_safe(ap, tmp, &aliases_lookup, link) {
+ if (strcmp(ap->alias, name) != 0)
+ continue;
+ __of_alias_del(ap);
+ return;
+ }
+}
+
+static void *alias_alloc(u64 size, u64 align)
+{
+ return kzalloc(size, GFP_KERNEL);
+}
+
+/* Callers must hold @aliases_mutex. */
+static void of_aliases_forget_all(void)
+{
+ struct alias_prop *ap, *tmp;
+
+ list_for_each_entry_safe(ap, tmp, &aliases_lookup, link)
+ __of_alias_del(ap);
+}
+
+static int of_aliases_reconfig_notifier(struct notifier_block *nb,
+ unsigned long action, void *arg)
+{
+ struct of_reconfig_data *rd = arg;
+
+ /* of_aliases may still be NULL when an overlay creates the node */
+ if (!rd->dn || !of_node_is_aliases(rd->dn))
+ return NOTIFY_DONE;
+
+ mutex_lock(&aliases_mutex);
+ switch (action) {
+ case OF_RECONFIG_ATTACH_NODE:
+ if (!of_aliases)
+ of_aliases = of_node_get(rd->dn);
+ break;
+ case OF_RECONFIG_DETACH_NODE:
+ if (of_aliases == rd->dn) {
+ of_aliases = NULL;
+ of_aliases_forget_all();
+ of_node_put(rd->dn);
+ }
+ break;
+ case OF_RECONFIG_ADD_PROPERTY:
+ of_alias_create(rd->prop, alias_alloc, true);
+ break;
+ case OF_RECONFIG_REMOVE_PROPERTY:
+ of_alias_destroy(rd->prop->name);
+ break;
+ case OF_RECONFIG_UPDATE_PROPERTY:
+ if (rd->old_prop)
+ of_alias_destroy(rd->old_prop->name);
+ of_alias_create(rd->prop, alias_alloc, true);
+ break;
+ default:
+ break;
+ }
+ mutex_unlock(&aliases_mutex);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block of_aliases_nb = {
+ .notifier_call = of_aliases_reconfig_notifier,
+};
+
+static int __init of_aliases_reconfig_init(void)
+{
+ return of_reconfig_notifier_register(&of_aliases_nb);
+}
+
+/* of_alias_scan() runs pre-initcall, so the boot-time scan is complete */
+core_initcall_sync(of_aliases_reconfig_init);
+#endif /* CONFIG_OF_DYNAMIC */
+
/**
* of_alias_scan - Scan all properties of the 'aliases' node
* @dt_alloc: An allocator that provides a virtual address to memory
@@ -1969,42 +2122,8 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
if (!of_aliases)
return;
- for_each_property_of_node(of_aliases, pp) {
- const char *start = pp->name;
- const char *end = start + strlen(start);
- struct device_node *np;
- struct alias_prop *ap;
- int id, len;
-
- /* Skip those we do not want to proceed */
- if (is_pseudo_property(pp->name))
- continue;
-
- np = of_find_node_by_path(pp->value);
- if (!np)
- continue;
-
- /* walk the alias backwards to extract the id and work out
- * the 'stem' string */
- while (end > start && isdigit(*(end - 1)))
- end--;
- len = end - start;
-
- if (kstrtoint(end, 10, &id) < 0) {
- of_node_put(np);
- continue;
- }
-
- /* Allocate an alias_prop with enough space for the stem */
- ap = dt_alloc(sizeof(*ap) + len + 1, __alignof__(*ap));
- if (!ap) {
- of_node_put(np);
- continue;
- }
- memset(ap, 0, sizeof(*ap) + len + 1);
- ap->alias = start;
- of_alias_add(ap, np, id, start, len);
- }
+ for_each_property_of_node(of_aliases, pp)
+ of_alias_create(pp, dt_alloc, false);
}
/**
@@ -2022,7 +2141,7 @@ int of_alias_get_id(const struct device_node *np, const char *stem)
struct alias_prop *app;
int id = -ENODEV;
- mutex_lock(&of_mutex);
+ mutex_lock(&aliases_mutex);
list_for_each_entry(app, &aliases_lookup, link) {
if (strcmp(app->stem, stem) != 0)
continue;
@@ -2032,7 +2151,7 @@ int of_alias_get_id(const struct device_node *np, const char *stem)
break;
}
}
- mutex_unlock(&of_mutex);
+ mutex_unlock(&aliases_mutex);
return id;
}
@@ -2050,7 +2169,7 @@ int of_alias_get_highest_id(const char *stem)
struct alias_prop *app;
int id = -ENODEV;
- mutex_lock(&of_mutex);
+ mutex_lock(&aliases_mutex);
list_for_each_entry(app, &aliases_lookup, link) {
if (strcmp(app->stem, stem) != 0)
continue;
@@ -2058,7 +2177,7 @@ int of_alias_get_highest_id(const char *stem)
if (app->id > id)
id = app->id;
}
- mutex_unlock(&of_mutex);
+ mutex_unlock(&aliases_mutex);
return id;
}
diff --git a/drivers/of/device.c b/drivers/of/device.c
index be4e1584e0af..5ca249fca02f 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -238,7 +238,7 @@ void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
add_uevent_var(env, "OF_COMPATIBLE_N=%d", seen);
seen = 0;
- mutex_lock(&of_mutex);
+ mutex_lock(&aliases_mutex);
list_for_each_entry(app, &aliases_lookup, link) {
if (dev->of_node == app->np) {
add_uevent_var(env, "OF_ALIAS_%d=%s", seen,
@@ -246,7 +246,7 @@ void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
seen++;
}
}
- mutex_unlock(&of_mutex);
+ mutex_unlock(&aliases_mutex);
}
EXPORT_SYMBOL_GPL(of_device_uevent);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 9bba999f0bf8..731b606ae3e3 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -17,6 +17,11 @@
* @alias: Alias property name
* @np: Pointer to device_node that the alias stands for
* @id: Index value from end of alias name
+ * @owned: True for runtime entries, where the struct and @alias are
+ * kmalloc'd/kstrdup'd and freed on removal. False for boot-time
+ * entries, which live in memblock (@alias points into the FDT)
+ * and are only unlinked. Every entry holds a reference on @np;
+ * removal drops it regardless of @owned.
* @stem: Alias string without the index
*
* The structure represents one alias property of 'aliases' node as
@@ -27,6 +32,7 @@ struct alias_prop {
const char *alias;
struct device_node *np;
int id;
+ bool owned;
char stem[];
};
@@ -40,6 +46,7 @@ struct alias_prop {
extern struct mutex of_mutex;
extern raw_spinlock_t devtree_lock;
+extern struct mutex aliases_mutex;
extern struct list_head aliases_lookup;
extern struct kset *of_kset;
@@ -223,6 +230,13 @@ static inline bool of_alias_value_ok(const struct property *pp)
strnlen(pp->value, pp->length) < pp->length;
}
+/* the /aliases node: root child with the exact name "aliases" */
+static inline bool of_node_is_aliases(const struct device_node *np)
+{
+ return of_node_is_root(np->parent) &&
+ !strcmp(kbasename(np->full_name), "aliases");
+}
+
#if IS_ENABLED(CONFIG_KUNIT)
int __of_address_resource_bounds(struct resource *r, u64 start, u64 size);
#endif
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH v8 4/6] of: update /aliases lookup on reconfig notifications
2026-10-14 23:17 ` [PATCH v8 4/6] of: update /aliases lookup on reconfig notifications Abdurrahman Hussain
@ 2026-10-14 23:29 ` sashiko-bot
0 siblings, 0 replies; 10+ messages in thread
From: sashiko-bot @ 2026-10-14 23:29 UTC (permalink / raw)
To: Abdurrahman Hussain; +Cc: devicetree, robh, conor+dt
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] of: UAF in of_find_node_opts_by_path() due to lockless read of of_aliases
--
commit b06b8f06ef78bdf618e4aa0aefa4a93a890ea63d
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>
of: update /aliases lookup on reconfig notifications
This commit introduces a reconfig notifier to dynamically update the /aliases
lookup table when device tree overlays add or remove aliases. It mirrors
property changes into aliases_lookup and manages entries added at runtime
versus boot time. An aliases_mutex is added to protect the lookup list.
Link: https://lore.kernel.org/lkml/1435675876-2159-1-git-send-email-geert+renesas@glider.be/ [1]
Link: https://lore.kernel.org/lkml/20150630172131.D4E6CC4041A@trevor.secretlab.ca/ [2]
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 6a6d9f8439dd1..b70dedce06fe4 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
[ ... ]
> @@ -1934,6 +1934,159 @@ static void of_alias_add(struct alias_prop *ap, struct device_node *np,
> ap->alias, ap->stem, ap->id, np);
> }
>
[ ... ]
> +static int of_aliases_reconfig_notifier(struct notifier_block *nb,
> + unsigned long action, void *arg)
> +{
> + struct of_reconfig_data *rd = arg;
> +
> + /* of_aliases may still be NULL when an overlay creates the node */
> + if (!rd->dn || !of_node_is_aliases(rd->dn))
> + return NOTIFY_DONE;
> +
> + mutex_lock(&aliases_mutex);
> + switch (action) {
> + case OF_RECONFIG_ATTACH_NODE:
> + if (!of_aliases)
> + of_aliases = of_node_get(rd->dn);
> + break;
> + case OF_RECONFIG_DETACH_NODE:
> + if (of_aliases == rd->dn) {
> + of_aliases = NULL;
> + of_aliases_forget_all();
> + of_node_put(rd->dn);
> + }
> + break;
[Severity: High]
Does this lockless read of of_aliases in of_find_node_opts_by_path() introduce
a Use-After-Free race?
The commit message states: "on DETACH the changeset holds its own references
across the notifier so the put here cannot be the final one while readers
still walk the node."
While the changeset holds a reference during the notifier, a reader in
of_find_node_opts_by_path() in drivers/of/base.c reading of_aliases is
completely lockless and not in an RCU read-side critical section. If the
reader thread is preempted immediately after loading the of_aliases pointer
but before calling of_node_get():
CPU1 (Reader)
of_find_node_opts_by_path()
// Starts executing: aliases = of_node_get(of_aliases);
// Reads global of_aliases pointer
<preempted>
CPU2 (Changeset detach)
of_aliases_reconfig_notifier()
of_aliases = NULL;
of_node_put(rd->dn);
<changeset completes detachment, drops its final reference>
<node is freed>
CPU1 (Reader resumes)
// Calls of_node_get() with the stale pointer
of_node_get(stale_pointer); // Use-After-Free
Can the reader be preempted long enough for the changeset detach to fully
complete and free the node before the reader increments the refcount?
> + case OF_RECONFIG_ADD_PROPERTY:
> + of_alias_create(rd->prop, alias_alloc, true);
> + break;
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-nh-of-alias-overlay-v8-0-0f74f05ac762@nexthop.ai?part=4
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v8 5/6] of/overlay: rewrite /aliases path values to live-tree paths
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
` (3 preceding siblings ...)
2026-10-14 23:17 ` [PATCH v8 4/6] of: update /aliases lookup on reconfig notifications Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
2026-10-14 23:27 ` sashiko-bot
2026-10-14 23:17 ` [PATCH v8 6/6] of: unittest: cover /aliases updates from overlay apply/revert Abdurrahman Hussain
5 siblings, 1 reply; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
An /aliases property added by an overlay references labeled nodes as
"&label", which dtc renders as an overlay-internal path such as
"/fragment@1/__overlay__/i2c@40000". The value is copied verbatim
into the live tree, of_find_node_by_path() cannot resolve it, and
of_alias_get_id() keeps returning -ENODEV.
/__symbols__ values follow the same convention and are already
rewritten by dup_and_fixup_symbol_prop(). Use it for properties of
the /aliases node too:
- a value that resolves inside one of the overlay's fragments is
stored rewritten to the live-tree path
- -ENODEV (legacy string aliases, absolute live-tree paths) is
copied verbatim, as before this series
- -EINVAL (not a NUL-terminated string) is copied verbatim with a
warning; consumers validate before dereferencing, and an overlay
that applied before this series keeps applying
- only -ENOMEM fails the apply
Pseudo-properties are exempt: the is_pseudo_property() check at the
top of add_changeset_property() only covers live-tree targets, and a
phandle of a newly created /aliases node is a cell, not a string.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
drivers/of/overlay.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index bc0c879dd807..2af9ffb08691 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -370,6 +370,19 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
if (IS_ERR(new_prop))
return PTR_ERR(new_prop);
+ } else if (!is_pseudo_property(overlay_prop->name) &&
+ of_node_is_aliases(target->np)) {
+ /* rewrite overlay-internal alias values to live-tree paths */
+ new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
+ if (new_prop == ERR_PTR(-ENOMEM))
+ return -ENOMEM;
+ if (IS_ERR(new_prop)) {
+ if (new_prop == ERR_PTR(-EINVAL))
+ pr_warn("%pOF/%s is not a valid string; alias will be inert\n",
+ target->np, overlay_prop->name);
+ /* not overlay-internal: copy verbatim, consumers validate */
+ new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
+ }
} else {
new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
}
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH v8 5/6] of/overlay: rewrite /aliases path values to live-tree paths
2026-10-14 23:17 ` [PATCH v8 5/6] of/overlay: rewrite /aliases path values to live-tree paths Abdurrahman Hussain
@ 2026-10-14 23:27 ` sashiko-bot
0 siblings, 0 replies; 10+ messages in thread
From: sashiko-bot @ 2026-10-14 23:27 UTC (permalink / raw)
To: Abdurrahman Hussain; +Cc: devicetree, robh, conor+dt
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] of: refcount underflow in dup_and_fixup_symbol_prop()
--
commit c5eaae3d3771753bc9d29f750410340abc26ee23
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>
of/overlay: rewrite /aliases path values to live-tree paths
This commit rewrites overlay-internal path values in the /aliases node
to live-tree paths so they can be properly resolved. It uses the existing
dup_and_fixup_symbol_prop() helper to accomplish this.
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
[ ... ]
> @@ -370,6 +370,19 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
> new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
> if (IS_ERR(new_prop))
> return PTR_ERR(new_prop);
> + } else if (!is_pseudo_property(overlay_prop->name) &&
> + of_node_is_aliases(target->np)) {
> + /* rewrite overlay-internal alias values to live-tree paths */
> + new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
[Severity: High]
Could this call to dup_and_fixup_symbol_prop() trigger a reference count
underflow?
Looking at dup_and_fixup_symbol_prop(), it retrieves nodes using
__of_find_node_by_path() but then explicitly drops references to them:
drivers/of/overlay.c:dup_and_fixup_symbol_prop() {
...
fragment_node = __of_find_node_by_path(ovcs->overlay_root, path + 1);
overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
of_node_put(fragment_node);
of_node_put(overlay_node);
...
}
However, as documented in drivers/of/of_private.h, __of_find_node_by_path()
operates without taking node references:
drivers/of/of_private.h:
/*
* All functions with two leading underscores operate
* without taking node references, so you either have to
* own the devtree lock or work on detached trees only.
*/
struct device_node *__of_find_node_by_path(const struct device_node *parent, ...);
Because the references were never initially acquired, calling of_node_put()
here will underflow the reference count. This drops the independent references
held by the changeset fragments and could lead to premature freeing of the
nodes and a use-after-free during subsequent access.
> + if (new_prop == ERR_PTR(-ENOMEM))
> + return -ENOMEM;
> + if (IS_ERR(new_prop)) {
> + if (new_prop == ERR_PTR(-EINVAL))
> + pr_warn("%pOF/%s is not a valid string; alias will be inert\n",
> + target->np, overlay_prop->name);
> + /* not overlay-internal: copy verbatim, consumers validate */
> + new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
> + }
> } else {
> new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
> }
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-nh-of-alias-overlay-v8-0-0f74f05ac762@nexthop.ai?part=5
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v8 6/6] of: unittest: cover /aliases updates from overlay apply/revert
2026-10-14 23:17 [PATCH v8 0/6] of: teach overlay code to keep /aliases in sync Abdurrahman Hussain
` (4 preceding siblings ...)
2026-10-14 23:17 ` [PATCH v8 5/6] of/overlay: rewrite /aliases path values to live-tree paths Abdurrahman Hussain
@ 2026-10-14 23:17 ` Abdurrahman Hussain
5 siblings, 0 replies; 10+ messages in thread
From: Abdurrahman Hussain @ 2026-10-14 23:17 UTC (permalink / raw)
To: Rob Herring, Saravana Kannan, Frank Rowand, David S. Miller,
Shawn Guo, Grant Likely, Grant Likely, Pantelis Antoniou,
David Daney, Krzysztof Kozlowski, Conor Dooley
Cc: devicetree, linux-kernel, Abdurrahman Hussain
Add overlay_alias.dtso and of_unittest_overlay_alias().
The overlay has two fragments: target-path="" grafts a labeled node
under the run-time target base, and target-path="/aliases" adds
`testcase-alias99 = &<label>` at the DT root. The runner applies it
with a non-NULL base via of_overlay_fdt_apply() (overlay_data_apply()
always passes NULL), asserts of_alias_get_id() on the grafted node
returns 99, reverts, and asserts of_alias_get_highest_id() reports
the stem gone. A precondition check runs before the apply.
This exercises the reconfig notifier, the absolute target-path
lookup, and the /aliases value rewrite together; any one missing
turns the get_id assertion into -ENODEV.
The grafted-node reference is dropped before of_overlay_remove():
overlay-created nodes must be back at refcount 1 when the changeset
is destroyed. The post-remove assertion uses of_alias_get_highest_id()
because it is keyed by stem and needs no node reference. The apply is
wrapped in EXPECT_BEGIN/END for the "memory leak will occur" warning
printed for properties added to nodes the overlay didn't create,
like the other overlay tests.
The overlay is not added to the fdtoverlay static build test:
fdtoverlay has no target-base concept, so the empty target-path
cannot be resolved statically.
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
drivers/of/unittest-data/Makefile | 5 ++
drivers/of/unittest-data/overlay_alias.dtso | 25 ++++++++++
drivers/of/unittest.c | 73 +++++++++++++++++++++++++++++
3 files changed, 103 insertions(+)
diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 01a966e39f23..fdfec5a7923b 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtbo.o \
overlay_18.dtbo.o \
overlay_19.dtbo.o \
overlay_20.dtbo.o \
+ overlay_alias.dtbo.o \
overlay_bad_add_dup_node.dtbo.o \
overlay_bad_add_dup_prop.dtbo.o \
overlay_bad_phandle.dtbo.o \
@@ -66,6 +67,10 @@ DTC_FLAGS_testcases += -Wno-interrupts_property \
# overlay_bad_add_dup_prop.dtbo \
# overlay_bad_phandle.dtbo \
# overlay_bad_symbol.dtbo \
+#
+# overlay_alias.dtbo needs a run-time target base for its empty target-path;
+# fdtoverlay has no equivalent, so it is also not included:
+# overlay_alias.dtbo \
apply_static_overlay_1 := overlay_0.dtbo \
overlay_1.dtbo \
diff --git a/drivers/of/unittest-data/overlay_alias.dtso b/drivers/of/unittest-data/overlay_alias.dtso
new file mode 100644
index 000000000000..17e02d1940f6
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_alias.dtso
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/*
+ * overlay_alias - declare an /aliases entry that points, via label, at a
+ * node grafted under the run-time target base (empty target-path).
+ */
+
+/ {
+ fragment@0 {
+ target-path = "";
+ __overlay__ {
+ testcase_target: alias-target {
+ };
+ };
+ };
+
+ fragment@1 {
+ target-path = "/aliases";
+ __overlay__ {
+ testcase-alias99 = &testcase_target;
+ };
+ };
+};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index e255f54f4d76..2f5e4056efae 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -3475,6 +3475,77 @@ static struct notifier_block of_nb = {
.notifier_call = of_notify,
};
+/* created by cmd_wrap_S_dtbo in scripts/Makefile.dtbs */
+extern uint8_t __dtbo_overlay_alias_begin[];
+extern uint8_t __dtbo_overlay_alias_end[];
+
+static void __init of_unittest_overlay_alias(void)
+{
+ const char *base_path =
+ "/testcase-data/overlay-node/test-bus/test-unittest100";
+ const char *target_path =
+ "/testcase-data/overlay-node/test-bus/test-unittest100/alias-target";
+ u32 size = __dtbo_overlay_alias_end - __dtbo_overlay_alias_begin;
+ struct device_node *base, *target;
+ int ovcs_id = 0;
+ int id, ret;
+
+ base = of_find_node_by_path(base_path);
+ if (!base) {
+ unittest(0, "could not find alias target base %s\n", base_path);
+ return;
+ }
+
+ id = of_alias_get_highest_id("testcase-alias");
+ if (id != -ENODEV) {
+ unittest(0, "unexpected testcase-alias%d before overlay apply\n",
+ id);
+ goto out_put_base;
+ }
+
+ EXPECT_BEGIN(KERN_INFO,
+ "OF: overlay: WARNING: memory leak will occur if overlay removed, property: /aliases/testcase-alias99");
+
+ ret = of_overlay_fdt_apply(__dtbo_overlay_alias_begin, size,
+ &ovcs_id, base);
+
+ EXPECT_END(KERN_INFO,
+ "OF: overlay: WARNING: memory leak will occur if overlay removed, property: /aliases/testcase-alias99");
+
+ if (ret < 0) {
+ unittest(0, "overlay_alias apply failed, ret = %d\n", ret);
+ if (ovcs_id)
+ of_overlay_remove(&ovcs_id);
+ goto out_put_base;
+ }
+
+ target = of_find_node_by_path(target_path);
+ if (!target) {
+ unittest(0, "could not find grafted target %s\n", target_path);
+ } else {
+ id = of_alias_get_id(target, "testcase-alias");
+ unittest(id == 99,
+ "of_alias_get_id() = %d after overlay apply, expected 99\n",
+ id);
+ /* changeset destroy expects overlay nodes back at refcount 1 */
+ of_node_put(target);
+ }
+
+ ret = of_overlay_remove(&ovcs_id);
+ if (ret) {
+ unittest(0, "overlay_alias remove failed, ret = %d\n", ret);
+ goto out_put_base;
+ }
+
+ id = of_alias_get_highest_id("testcase-alias");
+ unittest(id == -ENODEV,
+ "of_alias_get_highest_id() = %d after overlay remove, expected -ENODEV\n",
+ id);
+
+out_put_base:
+ of_node_put(base);
+}
+
static void __init of_unittest_overlay_notify(void)
{
int ovcs_id;
@@ -3649,6 +3720,8 @@ static void __init of_unittest_overlay(void)
of_unittest_overlay_gpio();
+ of_unittest_overlay_alias();
+
of_unittest_remove_tracked_overlays();
of_unittest_overlay_notify();
--
2.54.0
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