From: Tejun Heo Date: Mon, 5 May 2025 21:30:39 +0000 (-1000) Subject: sched_ext: bpf_iter_scx_dsq_new() should always initialize iterator X-Git-Tag: v6.15-rc7~35^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=428dc9fc0873989d73918d4a9cc22745b7bbc799;p=thirdparty%2Fkernel%2Flinux.git sched_ext: bpf_iter_scx_dsq_new() should always initialize iterator BPF programs may call next() and destroy() on BPF iterators even after new() returns an error value (e.g. bpf_for_each() macro ignores error returns from new()). bpf_iter_scx_dsq_new() could leave the iterator in an uninitialized state after an error return causing bpf_iter_scx_dsq_next() to dereference garbage data. Make bpf_iter_scx_dsq_new() always clear $kit->dsq so that next() and destroy() become noops. Signed-off-by: Tejun Heo Fixes: 650ba21b131e ("sched_ext: Implement DSQ iterator") Cc: stable@vger.kernel.org # v6.12+ Acked-by: Andrea Righi --- diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 4e37b40ce280c..f5133249fd4d9 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6827,6 +6827,12 @@ __bpf_kfunc int bpf_iter_scx_dsq_new(struct bpf_iter_scx_dsq *it, u64 dsq_id, BUILD_BUG_ON(__alignof__(struct bpf_iter_scx_dsq_kern) != __alignof__(struct bpf_iter_scx_dsq)); + /* + * next() and destroy() will be called regardless of the return value. + * Always clear $kit->dsq. + */ + kit->dsq = NULL; + if (flags & ~__SCX_DSQ_ITER_USER_FLAGS) return -EINVAL;