From: KP Singh kpsingh@kernel.org
[ Upstream commit b0fd1852bcc21accca6260ef245356d5c141ff66 ]
When task local storage was generalized for tracing programs, the bpf_task_local_storage callback was moved from a BPF LSM hook callback for security_task_free LSM hook to it's own callback. But a failure case in bad_fork_cleanup_security was missed which, when triggered, led to a dangling task owner pointer and a subsequent use-after-free. Move the bpf_task_storage_free to the very end of free_task to handle all failure cases.
This issue was noticed when a BPF LSM program was attached to the task_alloc hook on a kernel with KASAN enabled. The program used bpf_task_storage_get to copy the task local storage from the current task to the new task being created.
Fixes: a10787e6d58c ("bpf: Enable task local storage for tracing programs") Reported-by: Kuba Piecuch jpiecuch@google.com Signed-off-by: KP Singh kpsingh@kernel.org Acked-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20230602002612.1117381-1-kpsingh@kernel.org Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/fork.c b/kernel/fork.c index ec913b13c5edb..6bb91fbbf73cc 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -559,6 +559,7 @@ void free_task(struct task_struct *tsk) arch_release_task_struct(tsk); if (tsk->flags & PF_KTHREAD) free_kthread_struct(tsk); + bpf_task_storage_free(tsk); free_task_struct(tsk); } EXPORT_SYMBOL(free_task); @@ -843,7 +844,6 @@ void __put_task_struct(struct task_struct *tsk) cgroup_free(tsk); task_numa_free(tsk, true); security_task_free(tsk); - bpf_task_storage_free(tsk); exit_creds(tsk); delayacct_tsk_free(tsk); put_signal_struct(tsk->signal);