| Message ID | 1470233581-25728-1-git-send-email-dforster@brocade.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: David Forster <dforster@brocade.com> Date: Wed, 3 Aug 2016 15:13:01 +0100 > Panic occurs when issuing "cat /proc/net/route" whilst > populating FIB with > 1M routes. > > Use of cached node pointer in fib_route_get_idx is unsafe. ... > Signed-off-by: Dave Forster <dforster@brocade.com> Alexander, please review. Thanks.
On Wed, Aug 3, 2016 at 12:01 PM, David Miller <davem@davemloft.net> wrote: > From: David Forster <dforster@brocade.com> > Date: Wed, 3 Aug 2016 15:13:01 +0100 > >> Panic occurs when issuing "cat /proc/net/route" whilst >> populating FIB with > 1M routes. >> >> Use of cached node pointer in fib_route_get_idx is unsafe. > ... >> Signed-off-by: Dave Forster <dforster@brocade.com> > > Alexander, please review. > > Thanks. It took me a bit to recall how this worked. This looks good to me. By the way, I am glad you emailed my Gmail because my Mirantis email is no more, I am back to working for Intel. Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index d07fc07..febca0f 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2452,9 +2452,7 @@ struct fib_route_iter { static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter, loff_t pos) { - struct fib_table *tb = iter->main_tb; struct key_vector *l, **tp = &iter->tnode; - struct trie *t; t_key key; /* use cache location of next-to-find key */ @@ -2462,8 +2460,6 @@ static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter, pos -= iter->pos; key = iter->key; } else { - t = (struct trie *)tb->tb_data; - iter->tnode = t->kv; iter->pos = 0; key = 0; } @@ -2504,12 +2500,12 @@ static void *fib_route_seq_start(struct seq_file *seq, loff_t *pos) return NULL; iter->main_tb = tb; + t = (struct trie *)tb->tb_data; + iter->tnode = t->kv; if (*pos != 0) return fib_route_get_idx(iter, *pos); - t = (struct trie *)tb->tb_data; - iter->tnode = t->kv; iter->pos = 0; iter->key = 0;
Panic occurs when issuing "cat /proc/net/route" whilst populating FIB with > 1M routes. Use of cached node pointer in fib_route_get_idx is unsafe. BUG: unable to handle kernel paging request at ffffc90001630024 IP: [<ffffffff814cf6a0>] leaf_walk_rcu+0x10/0xe0 PGD 11b08d067 PUD 11b08e067 PMD dac4b067 PTE 0 Oops: 0000 [#1] SMP Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscac snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep virti acpi_cpufreq button parport_pc ppdev lp parport autofs4 ext4 crc16 mbcache jbd tio_ring virtio floppy uhci_hcd ehci_hcd usbcore usb_common libata scsi_mod CPU: 1 PID: 785 Comm: cat Not tainted 4.2.0-rc8+ #4 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 task: ffff8800da1c0bc0 ti: ffff88011a05c000 task.ti: ffff88011a05c000 RIP: 0010:[<ffffffff814cf6a0>] [<ffffffff814cf6a0>] leaf_walk_rcu+0x10/0xe0 RSP: 0018:ffff88011a05fda0 EFLAGS: 00010202 RAX: ffff8800d8a40c00 RBX: ffff8800da4af940 RCX: ffff88011a05ff20 RDX: ffffc90001630020 RSI: 0000000001013531 RDI: ffff8800da4af950 RBP: 0000000000000000 R08: ffff8800da1f9a00 R09: 0000000000000000 R10: ffff8800db45b7e4 R11: 0000000000000246 R12: ffff8800da4af950 R13: ffff8800d97a74c0 R14: 0000000000000000 R15: ffff8800d97a7480 FS: 00007fd3970e0700(0000) GS:ffff88011fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffffc90001630024 CR3: 000000011a7e4000 CR4: 00000000000006e0 Stack: ffffffff814d00d3 0000000000000000 ffff88011a05ff20 ffff8800da1f9a00 ffffffff811dd8b9 0000000000000800 0000000000020000 00007fd396f35000 ffffffff811f8714 0000000000003431 ffffffff8138dce0 0000000000000f80 Call Trace: [<ffffffff814d00d3>] ? fib_route_seq_start+0x93/0xc0 [<ffffffff811dd8b9>] ? seq_read+0x149/0x380 [<ffffffff811f8714>] ? fsnotify+0x3b4/0x500 [<ffffffff8138dce0>] ? process_echoes+0x70/0x70 [<ffffffff8121cfa7>] ? proc_reg_read+0x47/0x70 [<ffffffff811bb823>] ? __vfs_read+0x23/0xd0 [<ffffffff811bbd42>] ? rw_verify_area+0x52/0xf0 [<ffffffff811bbe61>] ? vfs_read+0x81/0x120 [<ffffffff811bcbc2>] ? SyS_read+0x42/0xa0 [<ffffffff81549ab2>] ? entry_SYSCALL_64_fastpath+0x16/0x75 Code: 48 85 c0 75 d8 f3 c3 31 c0 c3 f3 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 a 04 89 f0 33 02 44 89 c9 48 d3 e8 0f b6 4a 05 49 89 RIP [<ffffffff814cf6a0>] leaf_walk_rcu+0x10/0xe0 RSP <ffff88011a05fda0> CR2: ffffc90001630024 Signed-off-by: Dave Forster <dforster@brocade.com> --- net/ipv4/fib_trie.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)