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authorJosh Poimboeuf <jpoimboe@redhat.com>2015-01-20 09:26:18 -0600
committerJiri Kosina <jkosina@suse.cz>2015-01-20 20:09:41 +0100
commit83a90bb1345767f0cb96d242fd8b9db44b2b0e17 (patch)
tree68a4466302071ededbed9c50f4d80e431e656f32 /kernel/livepatch/core.c
parent32b7eb877165fdb29f1722071c6c64ced1789014 (diff)
downloadlinux-sh-83a90bb1345767f0cb96d242fd8b9db44b2b0e17.tar.gz
livepatch: enforce patch stacking semantics
Only allow the topmost patch on the stack to be enabled or disabled, so that patches can't be removed or added in an arbitrary order. Suggested-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'kernel/livepatch/core.c')
-rw-r--r--kernel/livepatch/core.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3d9c00b5223a..2401e7f955d3 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -379,6 +379,11 @@ static int __klp_disable_patch(struct klp_patch *patch)
struct klp_object *obj;
int ret;
+ /* enforce stacking: only the last enabled patch can be disabled */
+ if (!list_is_last(&patch->list, &klp_patches) &&
+ list_next_entry(patch, list)->state == KLP_ENABLED)
+ return -EBUSY;
+
pr_notice("disabling patch '%s'\n", patch->mod->name);
for (obj = patch->objs; obj->funcs; obj++) {
@@ -435,6 +440,11 @@ static int __klp_enable_patch(struct klp_patch *patch)
if (WARN_ON(patch->state != KLP_DISABLED))
return -EINVAL;
+ /* enforce stacking: only the first disabled patch can be enabled */
+ if (patch->list.prev != &klp_patches &&
+ list_prev_entry(patch, list)->state == KLP_DISABLED)
+ return -EBUSY;
+
pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);