3.6 KiB
CVE-2021-47127
Description
In the Linux kernel, the following vulnerability has been resolved:ice: track AF_XDP ZC enabled queues in bitmapCommit c7a219048e45 ("ice: Remove xsk_buff_pool from VSI structure")silently introduced a regression and broke the Tx side of AF_XDP in copymode. xsk_pool on ice_ring is set only based on the existence of the XDPprog on the VSI which in turn picks ice_clean_tx_irq_zc to be executed.That is not something that should happen for copy mode as it should usethe regular data path ice_clean_tx_irq.This results in a following splat when xdpsock is run in txonly or l2fwdscenarios in copy mode:[ 106.050195] BUG: kernel NULL pointer dereference, address: 0000000000000030[ 106.057269] #PF: supervisor read access in kernel mode[ 106.062493] #PF: error_code(0x0000) - not-present page[ 106.067709] PGD 0 P4D 0[ 106.070293] Oops: 0000 [#1] PREEMPT SMP NOPTI[ 106.074721] CPU: 61 PID: 0 Comm: swapper/61 Not tainted 5.12.0-rc2+ #45[ 106.081436] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019[ 106.092027] RIP: 0010:xp_raw_get_dma+0x36/0x50[ 106.096551] Code: 74 14 48 b8 ff ff ff ff ff ff 00 00 48 21 f0 48 c1 ee 30 48 01 c6 48 8b 87 90 00 00 00 48 89 f2 81 e6 ff 0f 00 00 48 c1 ea 0c <48> 8b 04 d0 48 83 e0 fe 48 01 f0 c3 66 66 2e 0f 1f 84 00 00 00 00[ 106.115588] RSP: 0018:ffffc9000d694e50 EFLAGS: 00010206[ 106.120893] RAX: 0000000000000000 RBX: ffff88984b8c8a00 RCX: ffff889852581800[ 106.128137] RDX: 0000000000000006 RSI: 0000000000000000 RDI: ffff88984cd8b800[ 106.135383] RBP: ffff888123b50001 R08: ffff889896800000 R09: 0000000000000800[ 106.142628] R10: 0000000000000000 R11: ffffffff826060c0 R12: 00000000000000ff[ 106.149872] R13: 0000000000000000 R14: 0000000000000040 R15: ffff888123b50018[ 106.157117] FS: 0000000000000000(0000) GS:ffff8897e0f40000(0000) knlGS:0000000000000000[ 106.165332] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033[ 106.171163] CR2: 0000000000000030 CR3: 000000000560a004 CR4: 00000000007706e0[ 106.178408] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000[ 106.185653] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400[ 106.192898] PKRU: 55555554[ 106.195653] Call Trace:[ 106.198143] [ 106.200196] ice_clean_tx_irq_zc+0x183/0x2a0 [ice][ 106.205087] ice_napi_poll+0x3e/0x590 [ice][ 106.209356] __napi_poll+0x2a/0x160[ 106.212911] net_rx_action+0xd6/0x200[ 106.216634] _do_softirq+0xbf/0x29b[ 106.220274] irq_exit_rcu+0x88/0xc0[ 106.223819] common_interrupt+0x7b/0xa0[ 106.227719] [ 106.229857] asm_common_interrupt+0x1e/0x40Fix this by introducing the bitmap of queues that are zero-copy enabled,where each bit, corresponding to a queue id that xsk pool is beingconfigured on, will be set/cleared within ice_xsk_pool{en,dis}able andchecked within ice_xsk_pool(). The latter is a function used fordeciding which napi poll routine is executed.Idea is being taken from our other drivers such as i40e and ixgbe.
POC
Reference
No PoCs from references.