diff mbox series

[v1,bpf-next,3/9] bpf: Fix __bpf_{list,rbtree}_add's beginning-of-node calculation

Message ID 20230504053338.1778690-4-davemarchevsky@fb.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf_refcount followups (part 1) | expand

Checks

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bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 47 this patch: 47
netdev/cc_maintainers warning 8 maintainers not CCed: yhs@fb.com kpsingh@kernel.org martin.lau@linux.dev john.fastabend@gmail.com song@kernel.org sdf@google.com jolsa@kernel.org haoluo@google.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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Commit Message

Dave Marchevsky May 4, 2023, 5:33 a.m. UTC 
Given the pointer to struct bpf_{rb,list}_node within a local kptr and
the byte offset of that field within the kptr struct, the calculation changed
by this patch is meant to find the beginning of the kptr so that it can
be passed to bpf_obj_drop.

Unfortunately instead of doing

  ptr_to_kptr = ptr_to_node_field - offset_bytes

the calculation is erroneously doing

  ptr_to_ktpr = ptr_to_node_field - (offset_bytes * sizeof(struct bpf_rb_node))

or the bpf_list_node equivalent.

This patch fixes the calculation.

Fixes: d2dcc67df910 ("bpf: Migrate bpf_rbtree_add and bpf_list_push_{front,back} to possibly fail")
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
---
 kernel/bpf/helpers.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index bb6b4637ebf2..7a8968839e91 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1950,7 +1950,7 @@  static int __bpf_list_add(struct bpf_list_node *node, struct bpf_list_head *head
 		INIT_LIST_HEAD(h);
 	if (!list_empty(n)) {
 		/* Only called from BPF prog, no need to migrate_disable */
-		__bpf_obj_drop_impl(n - off, rec);
+		__bpf_obj_drop_impl((void *)n - off, rec);
 		return -EINVAL;
 	}
 
@@ -2032,7 +2032,7 @@  static int __bpf_rbtree_add(struct bpf_rb_root *root, struct bpf_rb_node *node,
 
 	if (!RB_EMPTY_NODE(n)) {
 		/* Only called from BPF prog, no need to migrate_disable */
-		__bpf_obj_drop_impl(n - off, rec);
+		__bpf_obj_drop_impl((void *)n - off, rec);
 		return -EINVAL;
 	}