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| author | Jiayuan Chen <jiayuan.chen@linux.dev> | 2026-06-10 11:02:59 +0800 |
|---|---|---|
| committer | Florian Westphal <fw@strlen.de> | 2026-07-02 12:17:14 +0200 |
| commit | 43ae85af154b27f9a0ff602f7a01e3a7583ffdab (patch) | |
| tree | b14f498f6c6b4d53106230bfaeba4ad078ac451e | |
| parent | 78217fb2ccf9d3963dd32d86712ba42e7fd619a8 (diff) | |
| download | linux-stable-43ae85af154b27f9a0ff602f7a01e3a7583ffdab.tar.gz linux-stable-43ae85af154b27f9a0ff602f7a01e3a7583ffdab.zip | |
netfilter: ebtables: bound num_counters like nentries in do_replace()
do_replace_finish() allocates the counter buffer before it is validated:
counterstmp = vmalloc_array(repl->num_counters, sizeof(*counterstmp));
do_replace() only checks num_counters against INT_MAX / sizeof(struct
ebt_counter), so vmalloc_array() can be asked for up to 134217726 * 16 =
2147483616 bytes (~2 GiB).
num_counters must in fact equal nentries: do_replace_finish() later
rejects the request when repl->num_counters != t->private->nentries.
get_counters() folds the per-CPU counters back into one entry per rule,
so what userspace gets is bounded by nentries, never by nentries *
nr_cpus. Apply the same upper bound used for nentries (MAX_EBT_ENTRIES)
to the incoming num_counters so the over-sized allocation can no longer
be requested.
The allocation is still kept outside the ebt_mutex, since vmalloc() may
sleep and trigger reclaim; only the bound is tightened.
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Florian Westphal <fw@strlen.de>
| -rw-r--r-- | net/bridge/netfilter/ebtables.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index f20c039e44c8..042d31278713 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -39,6 +39,8 @@ #define COUNTER_OFFSET(n) (SMP_ALIGN(n * sizeof(struct ebt_counter))) #define COUNTER_BASE(c, n, cpu) ((struct ebt_counter *)(((char *)c) + \ COUNTER_OFFSET(n) * cpu)) +#define MAX_EBT_ENTRIES (((INT_MAX - sizeof(struct ebt_table_info)) / \ + NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) struct ebt_pernet { struct list_head tables; @@ -1124,10 +1126,9 @@ static int do_replace(struct net *net, sockptr_t arg, unsigned int len) return -EINVAL; /* overflow check */ - if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) / - NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) + if (tmp.nentries >= MAX_EBT_ENTRIES) return -ENOMEM; - if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter)) + if (tmp.num_counters >= MAX_EBT_ENTRIES) return -ENOMEM; tmp.name[sizeof(tmp.name) - 1] = 0; @@ -2265,10 +2266,9 @@ static int compat_copy_ebt_replace_from_user(struct ebt_replace *repl, if (tmp.entries_size == 0) return -EINVAL; - if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) / - NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) + if (tmp.nentries >= MAX_EBT_ENTRIES) return -ENOMEM; - if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter)) + if (tmp.num_counters >= MAX_EBT_ENTRIES) return -ENOMEM; memcpy(repl, &tmp, offsetof(struct ebt_replace, hook_entry)); |