4.19-stable review patch. If anyone has any objections, please let me know.
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From: Cosmin Ratiu cratiu@nvidia.com
[ Upstream commit 7c6782ad4911cbee874e85630226ed389ff2e453 ]
Previously, add_rule_fg would only add newly created rules from the handle into the tree when they had a refcount of 1. On the other hand, create_flow_handle tries hard to find and reference already existing identical rules instead of creating new ones.
These two behaviors can result in a situation where create_flow_handle 1) creates a new rule and references it, then 2) in a subsequent step during the same handle creation references it again, resulting in a rule with a refcount of 2 that is not linked into the tree, will have a NULL parent and root and will result in a crash when the flow group is deleted because del_sw_hw_rule, invoked on rule deletion, assumes node->parent is != NULL.
This happened in the wild, due to another bug related to incorrect handling of duplicate pkt_reformat ids, which lead to the code in create_flow_handle incorrectly referencing a just-added rule in the same flow handle, resulting in the problem described above. Full details are at [1].
This patch changes add_rule_fg to add new rules without parents into the tree, properly initializing them and avoiding the crash. This makes it more consistent with how rules are added to an FTE in create_flow_handle.
Fixes: 74491de93712 ("net/mlx5: Add multi dest support") Link: https://lore.kernel.org/netdev/ea5264d6-6b55-4449-a602-214c6f509c1e@163.com/... [1] Signed-off-by: Cosmin Ratiu cratiu@nvidia.com Reviewed-by: Tariq Toukan tariqt@nvidia.com Reviewed-by: Mark Bloch mbloch@nvidia.com Signed-off-by: Saeed Mahameed saeedm@nvidia.com Signed-off-by: Tariq Toukan tariqt@nvidia.com Link: https://lore.kernel.org/r/20240409190820.227554-5-tariqt@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c index f0aa7f0e54803..d2b8d284b1995 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c @@ -1452,8 +1452,9 @@ static struct mlx5_flow_handle *add_rule_fg(struct mlx5_flow_group *fg, } trace_mlx5_fs_set_fte(fte, false);
+ /* Link newly added rules into the tree. */ for (i = 0; i < handle->num_rules; i++) { - if (refcount_read(&handle->rule[i]->node.refcount) == 1) { + if (!handle->rule[i]->node.parent) { tree_add_node(&handle->rule[i]->node, &fte->node); trace_mlx5_fs_add_rule(handle->rule[i]); }