From 3941710a504a70502f3848145cee200807aae876 Mon Sep 17 00:00:00 2001 From: Yuan Chen Date: Wed, 23 Sep 2026 16:58:16 +0800 Subject: [PATCH 1/2] bpf: Fix range_tree_clear inconsistency on kmalloc_nolock failure in arena range_tree_clear() pre-allocates the right-half node before modifying the tree, so an allocation failure returns -ENOMEM without altering the range tree. Signed-off-by: Yuan Chen Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260923085817.365930-2-chenyuan_fl@163.com --- kernel/bpf/range_tree.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/range_tree.c b/kernel/bpf/range_tree.c index 2f28886f3ff7..15b588377a76 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -143,16 +143,22 @@ int range_tree_clear(struct range_tree *rt, u32 start, u32 len) if (rn->rn_start < start && rn->rn_last > last) { u32 old_last = rn->rn_last; + /* + * Pre-allocate the right-half node before modifying + * the tree. If allocation fails we return -ENOMEM + * without altering the range tree. + */ + new_rn = kmalloc_nolock(sizeof(struct range_node), + __GFP_ACCOUNT, NUMA_NO_NODE); + if (!new_rn) + return -ENOMEM; + /* Overlaps with the entire clearing range */ range_it_remove(rn, rt); rn->rn_last = start - 1; range_it_insert(rn, rt); - /* Add a range */ - new_rn = kmalloc_nolock(sizeof(struct range_node), __GFP_ACCOUNT, - NUMA_NO_NODE); - if (!new_rn) - return -ENOMEM; + /* Add right-half range */ new_rn->rn_start = last + 1; new_rn->rn_last = old_last; range_it_insert(new_rn, rt); From b51b058999e0c8ae6fc7b43ef31930e19c768859 Mon Sep 17 00:00:00 2001 From: Yuan Chen Date: Wed, 23 Sep 2026 16:58:17 +0800 Subject: [PATCH 2/2] bpf: Fix range_tree_set inconsistency on kmalloc_nolock failure in arena range_tree_set() pre-allocates the node needed for a brand-new range before calling range_tree_clear(), so an allocation failure returns -ENOMEM without having modified the tree (previously the overlapping nodes were already removed by range_tree_clear() before the allocation was attempted, permanently losing the cleared sub-ranges). The adjacency lookups done before the clear already return the nodes that the merge below needs: range_tree_clear() frees only the nodes that lie entirely inside [start, last], trims the overlapping ones in place, and the split case cannot happen because of the 'already set' check above. Do the lookup once and drop the unreachable -EFAULT checks. Signed-off-by: Yuan Chen Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260923085817.365930-3-chenyuan_fl@163.com --- kernel/bpf/range_tree.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/kernel/bpf/range_tree.c b/kernel/bpf/range_tree.c index 15b588377a76..2460e78d6a55 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -199,6 +199,7 @@ int is_range_tree_set(struct range_tree *rt, u32 start, u32 len) int range_tree_set(struct range_tree *rt, u32 start, u32 len) { u32 last = start + len - 1; + struct range_node *new_rn = NULL; struct range_node *right; struct range_node *left; int err; @@ -208,20 +209,19 @@ int range_tree_set(struct range_tree *rt, u32 start, u32 len) if (left && left->rn_start <= start && left->rn_last >= last) return 0; + left = range_it_iter_first(rt, start - 1, start - 1); + right = range_it_iter_first(rt, last + 1, last + 1); + if (!left && !right) { + new_rn = kmalloc_nolock(sizeof(struct range_node), + __GFP_ACCOUNT, NUMA_NO_NODE); + if (!new_rn) + return -ENOMEM; + } + /* Clear out everything in the range we want to set. */ err = range_tree_clear(rt, start, len); if (err) - return err; - - /* Do we have a left-adjacent range ? */ - left = range_it_iter_first(rt, start - 1, start - 1); - if (left && left->rn_last + 1 != start) - return -EFAULT; - - /* Do we have a right-adjacent range ? */ - right = range_it_iter_first(rt, last + 1, last + 1); - if (right && right->rn_start != last + 1) - return -EFAULT; + goto out_free_new; if (left && right) { /* Combine left and right adjacent ranges */ @@ -241,14 +241,16 @@ int range_tree_set(struct range_tree *rt, u32 start, u32 len) right->rn_start = start; range_it_insert(right, rt); } else { - left = kmalloc_nolock(sizeof(struct range_node), __GFP_ACCOUNT, NUMA_NO_NODE); - if (!left) - return -ENOMEM; - left->rn_start = start; - left->rn_last = last; - range_it_insert(left, rt); + /* No adjacent ranges; use the pre-allocated node */ + new_rn->rn_start = start; + new_rn->rn_last = last; + range_it_insert(new_rn, rt); } return 0; + +out_free_new: + kfree_nolock(new_rn); + return err; } void range_tree_destroy(struct range_tree *rt)