[ Upstream commit 49c2c3f246e2fc3009039e31a826333dcd0283cd ]

Commit 4a0e3e989d66 ("cdc_ncm: Add support for moving NDP to end of NCM frame") added logic to reserve space for the NDP at the end of the NTB/skb. This reservation did not take the final alignment of the NDP into account, causing us to reserve too little space. Additionally the padding prior to NDP addition did not ensure there was enough space for the NDP.

The NTB/skb with the NDP appended would then exceed the configured max size. This caused the final padding of the NTB to use a negative count, padding to almost INT_MAX, and resulting in:

[60103.825970] BUG: unable to handle kernel paging request at ffff9641f2004000 [60103.825998] IP: __memset+0x24/0x30 [60103.826001] PGD a6a06067 P4D a6a06067 PUD 4f65a063 PMD 72003063 PTE 0 [60103.826013] Oops: 0002 [#1] SMP NOPTI [60103.826018] Modules linked in: (removed( [60103.826158] CPU: 0 PID: 5990 Comm: Chrome_DevTools Tainted: G O 4.14.0-3-amd64 #1 Debian 4.14.17-1 [60103.826162] Hardware name: LENOVO 20081 BIOS 41CN28WW(V2.04) 05/03/2012 [60103.826166] task: ffff964193484fc0 task.stack: ffffb2890137c000 [60103.826171] RIP: 0010:__memset+0x24/0x30 [60103.826174] RSP: 0000:ffff964316c03b68 EFLAGS: 00010216 [60103.826178] RAX: 0000000000000000 RBX: 00000000fffffffd RCX: 000000001ffa5000 [60103.826181] RDX: 0000000000000005 RSI: 0000000000000000 RDI: ffff9641f2003ffc [60103.826184] RBP: ffff964192f6c800 R08: 00000000304d434e R09: ffff9641f1d2c004 [60103.826187] R10: 0000000000000002 R11: 00000000000005ae R12: ffff9642e6957a80 [60103.826190] R13: ffff964282ff2ee8 R14: 000000000000000d R15: ffff9642e4843900 [60103.826194] FS: 00007f395aaf6700(0000) GS:ffff964316c00000(0000) knlGS:0000000000000000 [60103.826197] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [60103.826200] CR2: ffff9641f2004000 CR3: 0000000013b0c000 CR4: 00000000000006f0 [60103.826204] Call Trace: [60103.826212] <IRQ> [60103.826225] cdc_ncm_fill_tx_frame+0x5e3/0x740 [cdc_ncm] [60103.826236] cdc_ncm_tx_fixup+0x57/0x70 [cdc_ncm] [60103.826246] usbnet_start_xmit+0x5d/0x710 [usbnet] [60103.826254] ? netif_skb_features+0x119/0x250 [60103.826259] dev_hard_start_xmit+0xa1/0x200 [60103.826267] sch_direct_xmit+0xf2/0x1b0 [60103.826273] __dev_queue_xmit+0x5e3/0x7c0 [60103.826280] ? ip_finish_output2+0x263/0x3c0 [60103.826284] ip_finish_output2+0x263/0x3c0 [60103.826289] ? ip_output+0x6c/0xe0 [60103.826293] ip_output+0x6c/0xe0 [60103.826298] ? ip_forward_options+0x1a0/0x1a0 [60103.826303] tcp_transmit_skb+0x516/0x9b0 [60103.826309] tcp_write_xmit+0x1aa/0xee0 [60103.826313] ? sch_direct_xmit+0x71/0x1b0 [60103.826318] tcp_tasklet_func+0x177/0x180 [60103.826325] tasklet_action+0x5f/0x110 [60103.826332] __do_softirq+0xde/0x2b3 [60103.826337] irq_exit+0xae/0xb0 [60103.826342] do_IRQ+0x81/0xd0 [60103.826347] common_interrupt+0x98/0x98 [60103.826351] </IRQ> [60103.826355] RIP: 0033:0x7f397bdf2282 [60103.826358] RSP: 002b:00007f395aaf57d8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff6e [60103.826362] RAX: 0000000000000000 RBX: 00002f07bc6d0900 RCX: 00007f39752d7fe7 [60103.826365] RDX: 0000000000000022 RSI: 0000000000000147 RDI: 00002f07baea02c0 [60103.826368] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 [60103.826371] R10: 00000000ffffffff R11: 0000000000000000 R12: 00002f07baea02c0 [60103.826373] R13: 00002f07bba227a0 R14: 00002f07bc6d090c R15: 0000000000000000 [60103.826377] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 [60103.826442] RIP: __memset+0x24/0x30 RSP: ffff964316c03b68 [60103.826444] CR2: ffff9641f2004000

Commit e1069bbfcf3b ("net: cdc_ncm: Reduce memory use when kernel memory low") made this bug much more likely to trigger by reducing the NTB size under memory pressure.

Link: https://bugs.debian.org/893393 Reported-by: Горбешко Богдан bodqhrohro@gmail.com Reported-and-tested-by: Dennis Wassenberg dennis.wassenberg@secunet.com Cc: Enrico Mioso mrkiko.rs@gmail.com Fixes: 4a0e3e989d66 ("cdc_ncm: Add support for moving NDP to end of NCM frame") [ bmork: tx_curr_size => tx_max and context fixup for v4.12 and older ] Signed-off-by: Bjørn Mork bjorn@mork.no Signed-off-by: David S. Miller davem@davemloft.net ---

This has already been applied to stable 4.14 and newer, but needed two minor changes for anything older than v4.13. The bug is only present in v4.3 and and newer, so there is no need to consider this backport for anything older than stable 4.4.

Please apply to 4.4 and 4.9 stable.

Thanks, Bjørn

drivers/net/usb/cdc_ncm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index feb61eaffe32..3086cae62fdc 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1124,7 +1124,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign) * accordingly. Otherwise, we should check here. */ if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) - delayed_ndp_size = ctx->max_ndp_size; + delayed_ndp_size = ALIGN(ctx->max_ndp_size, ctx->tx_ndp_modulus); else delayed_ndp_size = 0;

@@ -1257,7 +1257,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign) /* If requested, put NDP at end of frame. */ if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) { nth16 = (struct usb_cdc_ncm_nth16 *)skb_out->data; - cdc_ncm_align_tail(skb_out, ctx->tx_ndp_modulus, 0, ctx->tx_max); + cdc_ncm_align_tail(skb_out, ctx->tx_ndp_modulus, 0, ctx->tx_max - ctx->max_ndp_size); nth16->wNdpIndex = cpu_to_le16(skb_out->len); memcpy(skb_put(skb_out, ctx->max_ndp_size), ctx->delayed_ndp16, ctx->max_ndp_size);