diff mbox series

[net,04/10] net/mlx5: Properly link new fs rules into the tree

Message ID 20240326144646.2078893-5-saeed@kernel.org (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series [net,01/10] net/mlx5: E-switch, store eswitch pointer before registering devlink_param | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 944 this patch: 944
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 955 this patch: 955
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 955 this patch: 955
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 10 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-03-27--15-00 (tests: 952)

Commit Message

Saeed Mahameed March 26, 2024, 2:46 p.m. UTC 
From: Cosmin Ratiu <cratiu@nvidia.com>

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/T/#u [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>
---
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index e6bfa7e4f146..2a9421342a50 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -1808,8 +1808,9 @@  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]);
 		}