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: v6.0.16~223 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=82b39df5ddb298daaf6dc504032ff7eb027fa106;p=thirdparty%2Fkernel%2Fstable.git 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@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 Signed-off-by: Sasha Levin --- diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0e758911d963f..6b6fb7237ebea 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3505,9 +3505,9 @@ 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;