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authorChengming Zhou <chengming.zhou@linux.dev>2024-05-13 06:07:56 +0300
committerAndrew Morton <akpm@linux-foundation.org>2024-05-24 21:55:08 +0300
commit90e823498881fb8a91d83e9a8eed87c8c3ff2176 (patch)
tree6e62d929cf84ea3b5b4831c976807c8960801218
parent8cf360b9d6a840700e06864236a01a883b34bbad (diff)
downloadlinux-90e823498881fb8a91d83e9a8eed87c8c3ff2176.tar.xz
mm/ksm: fix possible UAF of stable_node
The commit 2c653d0ee2ae ("ksm: introduce ksm_max_page_sharing per page deduplication limit") introduced a possible failure case in the stable_tree_insert(), where we may free the new allocated stable_node_dup if we fail to prepare the missing chain node. Then that kfolio return and unlock with a freed stable_node set... And any MM activities can come in to access kfolio->mapping, so UAF. Fix it by moving folio_set_stable_node() to the end after stable_node is inserted successfully. Link: https://lkml.kernel.org/r/20240513-b4-ksm-stable-node-uaf-v1-1-f687de76f452@linux.dev Fixes: 2c653d0ee2ae ("ksm: introduce ksm_max_page_sharing per page deduplication limit") Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev> Acked-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/ksm.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index f5138f43f0d2..452ac8346e6e 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2153,7 +2153,6 @@ again:
INIT_HLIST_HEAD(&stable_node_dup->hlist);
stable_node_dup->kpfn = kpfn;
- folio_set_stable_node(kfolio, stable_node_dup);
stable_node_dup->rmap_hlist_len = 0;
DO_NUMA(stable_node_dup->nid = nid);
if (!need_chain) {
@@ -2172,6 +2171,8 @@ again:
stable_node_chain_add_dup(stable_node_dup, stable_node);
}
+ folio_set_stable_node(kfolio, stable_node_dup);
+
return stable_node_dup;
}