From 33d064aecd89846d5cf284ab75eeb9098b5ff49e Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 4 Mar 2024 12:19:40 +0100 Subject: [PATCH] efi: efivars: prevent double registration From: Johan Hovold [ Commit 0217a40d7ba6e71d7f3422fbe89b436e8ee7ece7 upstream ] Add the missing sanity check to efivars_register() so that it is no longer possible to override an already registered set of efivar ops (without first deregistering them). This can help debug initialisation ordering issues where drivers have so far unknowingly been relying on overriding the generic ops. Signed-off-by: Johan Hovold Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- drivers/firmware/efi/vars.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 0ba9f18312f5..4ca256bcd697 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -66,19 +66,28 @@ int efivars_register(struct efivars *efivars, const struct efivar_operations *ops, struct kobject *kobject) { + int rv; + if (down_interruptible(&efivars_lock)) return -EINTR; + if (__efivars) { + pr_warn("efivars already registered\n"); + rv = -EBUSY; + goto out; + } + efivars->ops = ops; efivars->kobject = kobject; __efivars = efivars; pr_info("Registered efivars operations\n"); - + rv = 0; +out: up(&efivars_lock); - return 0; + return rv; } EXPORT_SYMBOL_GPL(efivars_register);