From: Francesco Ruggeri fruggeri@arista.com

commit 8d29d16d21342a0c86405d46de0c4ac5daf1760f upstream

If a non zero value happens to be in xt[NFPROTO_BRIDGE].cur at init time, the following panic can be caused by running

% ebtables -t broute -F BROUTING

from a 32-bit user level on a 64-bit kernel. This patch replaces kmalloc_array with kcalloc when allocating xt.

[ 474.680846] BUG: unable to handle kernel paging request at 0000000009600920 [ 474.687869] PGD 2037006067 P4D 2037006067 PUD 2038938067 PMD 0 [ 474.693838] Oops: 0000 [#1] SMP [ 474.697055] CPU: 9 PID: 4662 Comm: ebtables Kdump: loaded Not tainted 4.19.17-11302235.AroraKernelnext.fc18.x86_64 #1 [ 474.707721] Hardware name: Supermicro X9DRT/X9DRT, BIOS 3.0 06/28/2013 [ 474.714313] RIP: 0010:xt_compat_calc_jump+0x2f/0x63 [x_tables] [ 474.720201] Code: 40 0f b6 ff 55 31 c0 48 6b ff 70 48 03 3d dc 45 00 00 48 89 e5 8b 4f 6c 4c 8b 47 60 ff c9 39 c8 7f 2f 8d 14 08 d1 fa 48 63 fa <41> 39 34 f8 4c 8d 0c fd 00 00 00 00 73 05 8d 42 01 eb e1 76 05 8d [ 474.739023] RSP: 0018:ffffc9000943fc58 EFLAGS: 00010207 [ 474.744296] RAX: 0000000000000000 RBX: ffffc90006465000 RCX: 0000000002580249 [ 474.751485] RDX: 00000000012c0124 RSI: fffffffff7be17e9 RDI: 00000000012c0124 [ 474.758670] RBP: ffffc9000943fc58 R08: 0000000000000000 R09: ffffffff8117cf8f [ 474.765855] R10: ffffc90006477000 R11: 0000000000000000 R12: 0000000000000001 [ 474.773048] R13: 0000000000000000 R14: ffffc9000943fcb8 R15: ffffc9000943fcb8 [ 474.780234] FS: 0000000000000000(0000) GS:ffff88a03f840000(0063) knlGS:00000000f7ac7700 [ 474.788612] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 474.794632] CR2: 0000000009600920 CR3: 0000002037422006 CR4: 00000000000606e0 [ 474.802052] Call Trace: [ 474.804789] compat_do_replace+0x1fb/0x2a3 [ebtables] [ 474.810105] compat_do_ebt_set_ctl+0x69/0xe6 [ebtables] [ 474.815605] ? try_module_get+0x37/0x42 [ 474.819716] compat_nf_setsockopt+0x4f/0x6d [ 474.824172] compat_ip_setsockopt+0x7e/0x8c [ 474.828641] compat_raw_setsockopt+0x16/0x3a [ 474.833220] compat_sock_common_setsockopt+0x1d/0x24 [ 474.838458] __compat_sys_setsockopt+0x17e/0x1b1 [ 474.843343] ? __check_object_size+0x76/0x19a [ 474.847960] __ia32_compat_sys_socketcall+0x1cb/0x25b [ 474.853276] do_fast_syscall_32+0xaf/0xf6 [ 474.857548] entry_SYSENTER_compat+0x6b/0x7a

Signed-off-by: Francesco Ruggeri fruggeri@arista.com Acked-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Zubin Mithra zsm@chromium.org --- Notes: * Syzkaller triggered a GPF in xt_compat_calc_jump with the following stacktrace when fuzzing a 4.14 kernel. Call Trace: compat_do_replace+0x5e3/0x7d0 net/bridge/netfilter/ebtables.c:2334 compat_do_ebt_set_ctl+0x264/0x2e2 net/bridge/netfilter/ebtables.c:2383 compat_nf_sockopt net/netfilter/nf_sockopt.c:144 [inline] compat_nf_setsockopt+0x90/0x130 net/netfilter/nf_sockopt.c:156 compat_ip_setsockopt net/ipv4/ip_sockglue.c:1281 [inline] compat_ip_setsockopt+0xb5/0xf0 net/ipv4/ip_sockglue.c:1262 inet_csk_compat_setsockopt+0x9e/0x130 net/ipv4/inet_connection_sock.c:1047 compat_tcp_setsockopt+0x45/0x80 net/ipv4/tcp.c:2816 compat_sock_common_setsockopt+0xb9/0x150 net/core/sock.c:3017 C_SYSC_setsockopt net/compat.c:404 [inline] compat_SyS_setsockopt+0x14a/0x390 net/compat.c:387 do_syscall_32_irqs_on arch/x86/entry/common.c:349 [inline] do_fast_syscall_32+0x3b4/0xc90 arch/x86/entry/common.c:412 entry_SYSENTER_compat+0x84/0x96 arch/x86/entry/entry_64_compat.S:139

* This patch resolves a conflict that arises when applying the original upstream commit. The conflict arises as the following upstream commit is not present in v4.14.y. 6da2ec56059c ("treewide: kmalloc() -> kmalloc_array()")

* This commit is present in linux-4.19.y

* Tests run: Chrome OS tryjobs, Syzkaller reproducer

net/netfilter/x_tables.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 8e054c63b54e..d42211a0b5e3 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -1798,7 +1798,7 @@ static int __init xt_init(void) seqcount_init(&per_cpu(xt_recseq, i)); }

- xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL); + xt = kcalloc(NFPROTO_NUMPROTO, sizeof(struct xt_af), GFP_KERNEL); if (!xt) return -ENOMEM;