[PATCH] kho: fix error handling in kho_add_subtree()

[PATCH] kho: fix error handling in kho_add_subtree()

[Breno Leitao]

Fix two error handling issues in kho_add_subtree(), where it doesn't
handle the error path correctly.

1. If fdt_setprop() fails after the subnode has been created, the
   subnode is not removed. This leaves an incomplete node in the FDT
   (missing "preserved-data" or "blob-size" properties).

2. The fdt_setprop() return value (an FDT error code) is stored
   directly in err and returned to the caller, which expects -errno.

Fix both by storing fdt_setprop() results in fdt_err, jumping to a new
out_del_node label that removes the subnode on failure, and only setting
err = 0 on the success path, otherwise returning -ENOMEM (instead of
FDT_ERR_ errors that would come from fdt_setprop).

Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers")
Suggested-by: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 kernel/liveupdate/kexec_handover.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 94762de1fe5f0..18509d8082ea7 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -762,19 +762,24 @@ int kho_add_subtree(const char *name, void *blob, size_t size)
 		goto out_pack;
 	}
 
-	err = fdt_setprop(root_fdt, off, KHO_SUB_TREE_PROP_NAME,
-			  &phys, sizeof(phys));
-	if (err < 0)
-		goto out_pack;
+	fdt_err = fdt_setprop(root_fdt, off, KHO_SUB_TREE_PROP_NAME,
+			      &phys, sizeof(phys));
+	if (fdt_err < 0)
+		goto out_del_node;
 
-	err = fdt_setprop(root_fdt, off, KHO_SUB_TREE_SIZE_PROP_NAME,
-			  &size_u64, sizeof(size_u64));
-	if (err < 0)
-		goto out_pack;
+	fdt_err = fdt_setprop(root_fdt, off, KHO_SUB_TREE_SIZE_PROP_NAME,
+			      &size_u64, sizeof(size_u64));
+	if (fdt_err < 0)
+		goto out_del_node;
 
 	WARN_ON_ONCE(kho_debugfs_blob_add(&kho_out.dbg, name, blob,
 					  size, false));
 
+	err = 0;
+	goto out_pack;
+
+out_del_node:
+	fdt_del_node(root_fdt, off);
 out_pack:
 	fdt_pack(root_fdt);
 

---
base-commit: 9763aa6c6df784d7159925c0b3bef4dfb791e84f
change-id: 20260407-kho_fix_send-ae33f16d7502

Best regards,
--  
Breno Leitao <leitao@debian.org>

Re: [PATCH] kho: fix error handling in kho_add_subtree()

[Mike Rapoport]

On Tue, Apr 07, 2026 at 10:01:47AM -0700, Breno Leitao wrote:
> Fix two error handling issues in kho_add_subtree(), where it doesn't
> handle the error path correctly.
> 
> 1. If fdt_setprop() fails after the subnode has been created, the
>    subnode is not removed. This leaves an incomplete node in the FDT
>    (missing "preserved-data" or "blob-size" properties).
> 
> 2. The fdt_setprop() return value (an FDT error code) is stored
>    directly in err and returned to the caller, which expects -errno.
> 
> Fix both by storing fdt_setprop() results in fdt_err, jumping to a new
> out_del_node label that removes the subnode on failure, and only setting
> err = 0 on the success path, otherwise returning -ENOMEM (instead of
> FDT_ERR_ errors that would come from fdt_setprop).
> 
> Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers")
> Suggested-by: Pratyush Yadav <pratyush@kernel.org>
> Signed-off-by: Breno Leitao <leitao@debian.org>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
>  kernel/liveupdate/kexec_handover.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)

-- 
Sincerely yours,
Mike.