This is a note to let you know that I've just added the patch titled bpf: prevent leak of lsm program after failed attach to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bpf-prevent-leak-of-lsm-program-after-failed-attach.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 9770f8c7e18ae8ae3617098ff0f672cef8b96a5b Author: Milan Landaverde <milan@xxxxxxxxxxxx> Date: Tue Dec 13 12:57:14 2022 -0500 bpf: prevent leak of lsm program after failed attach [ Upstream commit e89f3edffb860a0f54a9ed16deadb7a4a1fa3862 ] In [0], we added the ability to bpf_prog_attach LSM programs to cgroups, but in our validation to make sure the prog is meant to be attached to BPF_LSM_CGROUP, we return too early if the check fails. This results in lack of decrementing prog's refcnt (through bpf_prog_put) leaving the LSM program alive past the point of the expected lifecycle. This fix allows for the decrement to take place. [0] https://lore.kernel.org/all/20220628174314.1216643-4-sdf@xxxxxxxxxx/ Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") Signed-off-by: Milan Landaverde <milan@xxxxxxxxxxxx> Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Reviewed-by: Stanislav Fomichev <sdf@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221213175714.31963-1-milan@xxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7b373a5e861f..439ed7e5a82b 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3504,9 +3504,9 @@ static int bpf_prog_attach(const union bpf_attr *attr) case BPF_PROG_TYPE_LSM: if (ptype == BPF_PROG_TYPE_LSM && prog->expected_attach_type != BPF_LSM_CGROUP) - return -EINVAL; - - ret = cgroup_bpf_prog_attach(attr, ptype, prog); + ret = -EINVAL; + else + ret = cgroup_bpf_prog_attach(attr, ptype, prog); break; default: ret = -EINVAL;