5.15-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit add117e48df4788a86a21bd0515833c0a6db1ad1 ]
When allocating and building an afs_server_list struct object from a VLDB record, we look up each server address to get the server record for it - but a server may have more than one entry in the record and we discard the duplicate pointers. Currently, however, when we discard, we only put a server record, not unuse it - but the lookup got as an active-user count.
The active-user count on an afs_server_list object determines its lifetime whereas the refcount keeps the memory backing it around. Failing to reduce the active-user counter prevents the record from being cleaned up and can lead to multiple copied being seen - and pointing to deleted afs_cell objects and other such things.
Fix this by switching the incorrect 'put' to an 'unuse' instead.
Without this, occasionally, a dead server record can be seen in /proc/net/afs/servers and list corruption may be observed:
list_del corruption. prev->next should be ffff888102423e40, but was 0000000000000000. (prev=ffff88810140cd38)
Fixes: 977e5f8ed0ab ("afs: Split the usage count on struct afs_server") Signed-off-by: David Howells dhowells@redhat.com cc: Marc Dionne marc.dionne@auristor.com cc: Simon Horman horms@kernel.org cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250218192250.296870-5-dhowells@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/server_list.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/afs/server_list.c b/fs/afs/server_list.c index 4d6369477f54e..89c75d934f79e 100644 --- a/fs/afs/server_list.c +++ b/fs/afs/server_list.c @@ -67,8 +67,8 @@ struct afs_server_list *afs_alloc_server_list(struct afs_volume *volume, break; if (j < slist->nr_servers) { if (slist->servers[j].server == server) { - afs_put_server(volume->cell->net, server, - afs_server_trace_put_slist_isort); + afs_unuse_server(volume->cell->net, server, + afs_server_trace_put_slist_isort); continue; }