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SubjectRe: [PATCH] livepatch: Validate module/old func name length
On Fri, Jul 20, 2018 at 03:16:42PM +0530, Kamalesh Babulal wrote:
> livepatch module author can pass module name/old function name with more
> than the defined character limit. With obj->name length greater than
> MODULE_NAME_LEN, the livepatch module gets loaded but waits forever on
> the module specified by obj->name to be loaded. It also populates a /sys
> directory with an untruncated object name.
>
> In the case of funcs->old_name length greater then KSYM_NAME_LEN, it
> would not match against any of the symbol table entries. Instead loop
> through the symbol table comparing them against a nonexisting function,
> which can be avoided.
>
> The same issues apply, to misspelled/incorrect names. At least gatekeep
> the modules with over the limit string length, by checking for their
> length during livepatch module registration.
>
> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>

> ---
> kernel/livepatch/core.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 3a4656fb7047..5b77a7314e01 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -678,6 +678,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
> if (!func->old_name || !func->new_func)
> return -EINVAL;
>
> + if (strlen(func->old_name) >= KSYM_NAME_LEN)
> + return -EINVAL;
> +
> INIT_LIST_HEAD(&func->stack_node);
> func->patched = false;
> func->transition = false;
> @@ -751,6 +754,9 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
> if (!obj->funcs)
> return -EINVAL;
>
> + if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
> + return -EINVAL;
> +
> obj->patched = false;
> obj->mod = NULL;
>
> --
> 2.7.4
>

--
Josh

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