From: Daniel Gomez <[email protected]>
The -EEXIST error code is reserved by the module loading infrastructure
to indicate that a module is already loaded. When a module's init
function returns -EEXIST, userspace tools like kmod interpret this as
"module already loaded" and treat the operation as successful, returning
0 to the user even though the module initialization actually failed.
This follows the precedent set by commit 54416fd76770 ("netfilter:
conntrack: helper: Replace -EEXIST by -EBUSY") which fixed the same
issue in nf_conntrack_helper_register().
This affects bpf_crypto_skcipher module. While the configuration
required to build it as a module is unlikely in practice, it is
technically possible, so fix it for correctness.
Signed-off-by: Daniel Gomez <[email protected]>
---
The error code -EEXIST is reserved by the kernel module loader to
indicate that a module with the same name is already loaded. When a
module's init function returns -EEXIST, kmod interprets this as "module
already loaded" and reports success instead of failure [1].
The kernel module loader will include a safety net that provides -EEXIST
to -EBUSY with a warning [2], and a documentation patch has been sent to
prevent future occurrences [3].
These affected code paths were identified using a static analysis tool
[4] that traces -EEXIST returns to module_init(). The tool was developed
with AI assistance and all findings were manually validated.
Link: https://lore.kernel.org/all/[email protected]/ [1]
Link:
https://lore.kernel.org/all/[email protected]/
[2]
Link:
https://lore.kernel.org/all/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa7...@samsung.com/
[3]
Link: https://gitlab.com/-/snippets/4913469 [4]
---
kernel/bpf/crypto.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 83c4d9943084..1ab79a6dec84 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -60,7 +60,7 @@ struct bpf_crypto_ctx {
int bpf_crypto_register_type(const struct bpf_crypto_type *type)
{
struct bpf_crypto_type_list *node;
- int err = -EEXIST;
+ int err = -EBUSY;
down_write(&bpf_crypto_types_sem);
list_for_each_entry(node, &bpf_crypto_types, list) {
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251219-dev-module-init-eexists-bpf-da2aa3577437
Best regards,
--
Daniel Gomez <[email protected]>
