Patch "bpf: Re-enable unit_size checking for global per-cpu allocator" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    bpf: Re-enable unit_size checking for global per-cpu allocator

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bpf-re-enable-unit_size-checking-for-global-per-cpu-.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9f8ed0e217fc34f171d265bf9cdfe702786cce8f
Author: Hou Tao <houtao1@xxxxxxxxxx>
Date:   Fri Oct 20 21:31:58 2023 +0800

    bpf: Re-enable unit_size checking for global per-cpu allocator
    
    [ Upstream commit baa8fdecd87bb8751237b45e3bcb5a179e5a12ca ]
    
    With pcpu_alloc_size() in place, check whether or not the size of
    the dynamic per-cpu area is matched with unit_size.
    
    Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231020133202.4043247-4-houtao@xxxxxxxxxxxxxxx
    Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
    Stable-dep-of: 7ac5c53e0073 ("bpf: Use c->unit_size to select target cache during free")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index 956f80ee6f5c..9657d5951d78 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -491,21 +491,17 @@ static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
 	struct llist_node *first;
 	unsigned int obj_size;
 
-	/* For per-cpu allocator, the size of free objects in free list doesn't
-	 * match with unit_size and now there is no way to get the size of
-	 * per-cpu pointer saved in free object, so just skip the checking.
-	 */
-	if (c->percpu_size)
-		return 0;
-
 	first = c->free_llist.first;
 	if (!first)
 		return 0;
 
-	obj_size = ksize(first);
+	if (c->percpu_size)
+		obj_size = pcpu_alloc_size(((void **)first)[1]);
+	else
+		obj_size = ksize(first);
 	if (obj_size != c->unit_size) {
-		WARN_ONCE(1, "bpf_mem_cache[%u]: unexpected object size %u, expect %u\n",
-			  idx, obj_size, c->unit_size);
+		WARN_ONCE(1, "bpf_mem_cache[%u]: percpu %d, unexpected object size %u, expect %u\n",
+			  idx, c->percpu_size, obj_size, c->unit_size);
 		return -EINVAL;
 	}
 	return 0;
@@ -967,6 +963,12 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags)
 	return !ret ? NULL : ret + LLIST_NODE_SZ;
 }
 
+/* The alignment of dynamic per-cpu area is 8, so c->unit_size and the
+ * actual size of dynamic per-cpu area will always be matched and there is
+ * no need to adjust size_index for per-cpu allocation. However for the
+ * simplicity of the implementation, use an unified size_index for both
+ * kmalloc and per-cpu allocation.
+ */
 static __init int bpf_mem_cache_adjust_size(void)
 {
 	unsigned int size;