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| author | Chengming Zhou <chengming.zhou@linux.dev> | 2024-05-13 11:07:56 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-05-24 11:55:08 -0700 |
| commit | 90e823498881fb8a91d83e9a8eed87c8c3ff2176 (patch) | |
| tree | 6e62d929cf84ea3b5b4831c976807c8960801218 | |
| parent | 8cf360b9d6a840700e06864236a01a883b34bbad (diff) | |
| download | linux-90e823498881fb8a91d83e9a8eed87c8c3ff2176.tar.gz linux-90e823498881fb8a91d83e9a8eed87c8c3ff2176.tar.bz2 linux-90e823498881fb8a91d83e9a8eed87c8c3ff2176.zip | |
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.c | 3 |
1 files changed, 2 insertions, 1 deletions
@@ -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; } |