From: KP Singh <kpsingh@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230602002612.1117381-1-kpsingh@xxxxxxxxxx
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.39.2
