CVE-2021-47127

CVE-2021-47127 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: ice: track AF_XDP ZC enabled queues in bitmap Commit c7a219048e45 ("ice: Remove xsk_buff_pool from VSI structure") silently introduced a regression and broke the Tx side of AF_XDP in copy mode. xsk_pool on ice_ring is set only based on the existence of the XDP prog 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 use the regular data path ice_clean_tx_irq. This results in a following splat when xdpsock is run in txonly or l2fwd scenarios in copy mode: <snip> [ 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] <IRQ> [ 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] </IRQ> [ 106.229857] asm_common_interrupt+0x1e/0x40 </snip> Fix this by introducing the bitmap of queues that are zero-copy enabled, where each bit, corresponding to a queue id that xsk pool is being configured on, will be set/cleared within ice_xsk_pool_{en,dis}able and checked within ice_xsk_pool(). The latter is a function used for deciding which napi poll routine is executed. Idea is being taken from our other drivers such as i40e and ixgbe.

Frequently asked questions

What is CVE-2021-47127?
In the Linux kernel, the following vulnerability has been resolved: ice: track AF_XDP ZC enabled queues in bitmap Commit c7a219048e45 ("ice: Remove xsk_buff_pool from VSI structure") silently introduced a regression and broke the Tx side of AF_XDP in copy mode. xsk_pool on ice_ring is set only based on the existence of the XDP prog 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 use the regular data path ice_clean_tx_irq. This results in a following splat when xdpsock is run in txonly or l2fwd scenarios in copy mode: <snip> [ 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] <IRQ> [ 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] </IRQ> [ 106.229857] asm_common_interrupt+0x1e/0x40 </snip> Fix this by introducing the bitmap of queues that are zero-copy enabled, where each bit, corresponding to a queue id that xsk pool is being configured on, will be set/cleared within ice_xsk_pool_{en,dis}able and checked within ice_xsk_pool(). The latter is a function used for deciding which napi poll routine is executed. Idea is being taken from our other drivers such as i40e and ixgbe.
How severe is CVE-2021-47127?
CVE-2021-47127 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-47127 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-47127?
CVE-2021-47127 primarily affects Linux Linux Kernel. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-47127?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-47127 have an EU (EUVD) identifier?
Yes. CVE-2021-47127 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-33775.
When was CVE-2021-47127 published?
CVE-2021-47127 was published on 2024-03-15 and last updated on 2026-06-17.

References

Affected products (5)

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