In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: unconditionally flush pending work before notifier
syzbot reports:
KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831
KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530
KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597
Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45
[…]
Workqueue: events nf_tables_trans_destroy_work
Call Trace:
nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline]
nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline]
nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597
Problem is that the notifier does a conditional flush, but its possible
that the table-to-be-removed is still referenced by transactions being
processed by the worker, so we need to flush unconditionally.
We could make the flush_work depend on whether we found a table to delete
in nf-next to avoid the flush for most cases.
AFAICS this problem is only exposed in nf-next, with
commit e169285f8c56 (“netfilter: nf_tables: do not store nft_ctx in transaction objects”),
with this commit applied there is an unconditional fetch of
table->family which is whats triggering the above splat.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/netfilter/nf_tables_api.c"
],
"versions": [
{
"version": "f22954f8c58f",
"lessThan": "3325628cb36b",
"status": "affected",
"versionType": "git"
},
{
"version": "41841b585e53",
"lessThan": "4c06c13317b9",
"status": "affected",
"versionType": "git"
},
{
"version": "2c9f0293280e",
"lessThan": "55a40406aac5",
"status": "affected",
"versionType": "git"
},
{
"version": "2c9f0293280e",
"lessThan": "09e650c3a3a7",
"status": "affected",
"versionType": "git"
},
{
"version": "2c9f0293280e",
"lessThan": "9f6958ba2e90",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/netfilter/nf_tables_api.c"
],
"versions": [
{
"version": "6.5",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.5",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.15.163",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.98",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.39",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.9.9",
"lessThanOrEqual": "6.9.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.10",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]
git.kernel.org/stable/c/09e650c3a3a7d804430260510534ccbf71c75b2e
git.kernel.org/stable/c/3325628cb36b7f216c5716e7b5124d9dc81199e4
git.kernel.org/stable/c/4c06c13317b9a08decedcd7aaf706691e336277c
git.kernel.org/stable/c/55a40406aac555defe9bdd0adec9508116ce7cb1
git.kernel.org/stable/c/9f6958ba2e902f9820c594869bd710ba74b7c4c0