From: Milan Landaverde Date: Tue, 13 Dec 2022 17:57:14 +0000 (-0500) Subject: bpf: prevent leak of lsm program after failed attach X-Git-Tag: v6.6.17~5865^2~16^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e89f3edffb860a0f54a9ed16deadb7a4a1fa3862;p=platform%2Fkernel%2Flinux-rpi.git bpf: prevent leak of lsm program after failed attach 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@google.com/ Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") Signed-off-by: Milan Landaverde Signed-off-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann Reviewed-by: Stanislav Fomichev Link: https://lore.kernel.org/r/20221213175714.31963-1-milan@mdaverde.com --- diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 35972af..64131f8 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3518,9 +3518,9 @@ 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;