"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: unconditionally flush pending work before notifier\n\nsyzbot reports:\n\nKASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831\nKASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530\nKASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597\nRead of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45\n[..]\nWorkqueue: events nf_tables_trans_destroy_work\nCall Trace:\n nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline]\n nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline]\n nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597\n\nProblem is that the notifier does a conditional flush, but its possible\nthat the table-to-be-removed is still referenced by transactions being\nprocessed by the worker, so we need to flush unconditionally.\n\nWe could make the flush_work depend on whether we found a table to delete\nin nf-next to avoid the flush for most cases.\n\nAFAICS this problem is only exposed in nf-next, with\ncommit e169285f8c56 (\"netfilter: nf_tables: do not store nft_ctx in transaction objects\"),\nwith this commit applied there is an unconditional fetch of\ntable->family which is whats triggering the above splat."
