| Message ID | 20220518160022.224294-1-pablo@netfilter.org |
|---|---|
| State | Superseded |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [nf,v2] netfilter: nf_tables: disable bh to update per-cpu rnd_state | expand |
Pablo Neira Ayuso <pablo@netfilter.org> wrote: > bh might occur while updating per-cpu rnd_state from user context, > ie. local_out path. > > [233241.951068] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 > [233241.951220] caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] > [233241.951225] CPU: 2 PID: 2725 Comm: nginx Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 > [233241.951227] Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 > [233241.951228] Call Trace: > [233241.951231] <TASK> > [233241.951233] dump_stack_lvl+0x48/0x5e > [233241.951236] check_preemption_disabled+0xde/0xe0 > [233241.951239] nft_ng_random_eval+0x24/0x54 [nft_numgen] > > Fixes: 6b2faee0ca91 ("netfilter: nft_meta: place prandom handling in a helper") > Fixes: 978d8f9055c3 ("netfilter: nft_numgen: add map lookups for numgen random operations") > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> > --- > v2: disable/enable bh > @Florian: your rand meta support is missing {disable,enable}_local_bh() I wonder if its better to just switch to get_random_u32() instead of prandom.
On Wed, May 18, 2022 at 06:46:21PM +0200, Florian Westphal wrote: > Pablo Neira Ayuso <pablo@netfilter.org> wrote: > > bh might occur while updating per-cpu rnd_state from user context, > > ie. local_out path. > > > > [233241.951068] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 > > [233241.951220] caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] > > [233241.951225] CPU: 2 PID: 2725 Comm: nginx Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 > > [233241.951227] Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 > > [233241.951228] Call Trace: > > [233241.951231] <TASK> > > [233241.951233] dump_stack_lvl+0x48/0x5e > > [233241.951236] check_preemption_disabled+0xde/0xe0 > > [233241.951239] nft_ng_random_eval+0x24/0x54 [nft_numgen] > > > > Fixes: 6b2faee0ca91 ("netfilter: nft_meta: place prandom handling in a helper") > > Fixes: 978d8f9055c3 ("netfilter: nft_numgen: add map lookups for numgen random operations") > > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> > > --- > > v2: disable/enable bh > > @Florian: your rand meta support is missing {disable,enable}_local_bh() > > I wonder if its better to just switch to get_random_u32() instead of prandom. Feel free to pick if you would like to send a v3.
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c index ac4859241e17..30aded940f91 100644 --- a/net/netfilter/nft_meta.c +++ b/net/netfilter/nft_meta.c @@ -273,9 +273,15 @@ static bool nft_meta_get_eval_ifname(enum nft_meta_keys key, u32 *dest, static noinline u32 nft_prandom_u32(void) { - struct rnd_state *state = this_cpu_ptr(&nft_prandom_state); + struct rnd_state *state; + u32 ret; - return prandom_u32_state(state); + local_bh_disable(); + state = this_cpu_ptr(&nft_prandom_state); + ret = prandom_u32_state(state); + local_bh_enable(); + + return ret; } #ifdef CONFIG_IP_ROUTE_CLASSID diff --git a/net/netfilter/nft_numgen.c b/net/netfilter/nft_numgen.c index 81b40c663d86..911589ad3837 100644 --- a/net/netfilter/nft_numgen.c +++ b/net/netfilter/nft_numgen.c @@ -137,10 +137,15 @@ struct nft_ng_random { static u32 nft_ng_random_gen(struct nft_ng_random *priv) { - struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); + struct rnd_state *state; + u32 ret; - return reciprocal_scale(prandom_u32_state(state), priv->modulus) + - priv->offset; + local_bh_disable(); + state = this_cpu_ptr(&nft_numgen_prandom_state); + ret = prandom_u32_state(state); + local_bh_enable(); + + return reciprocal_scale(ret, priv->modulus) + priv->offset; } static void nft_ng_random_eval(const struct nft_expr *expr,
bh might occur while updating per-cpu rnd_state from user context, ie. local_out path. [233241.951068] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 [233241.951220] caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] [233241.951225] CPU: 2 PID: 2725 Comm: nginx Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 [233241.951227] Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 [233241.951228] Call Trace: [233241.951231] <TASK> [233241.951233] dump_stack_lvl+0x48/0x5e [233241.951236] check_preemption_disabled+0xde/0xe0 [233241.951239] nft_ng_random_eval+0x24/0x54 [nft_numgen] Fixes: 6b2faee0ca91 ("netfilter: nft_meta: place prandom handling in a helper") Fixes: 978d8f9055c3 ("netfilter: nft_numgen: add map lookups for numgen random operations") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> --- v2: disable/enable bh @Florian: your rand meta support is missing {disable,enable}_local_bh() net/netfilter/nft_meta.c | 10 ++++++++-- net/netfilter/nft_numgen.c | 11 ++++++++--- 2 files changed, 16 insertions(+), 5 deletions(-)