6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tejun Heo tj@kernel.org
commit 428dc9fc0873989d73918d4a9cc22745b7bbc799 upstream.
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 tj@kernel.org Fixes: 650ba21b131e ("sched_ext: Implement DSQ iterator") Cc: stable@vger.kernel.org # v6.12+ Acked-by: Andrea Righi arighi@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/sched/ext.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6731,6 +6731,12 @@ __bpf_kfunc int bpf_iter_scx_dsq_new(str 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;