Oracle Linux: CVE-2024-49949: ELSA-2024-10939: kernel security update (MODERATE) (Multiple Advisories)

Oracle Linux: CVE-2024-49949: ELSA-2024-10939:kernel security update (MODERATE) (Multiple Advisories)

Severity

5

CVSS

(AV:L/AC:L/Au:S/C:N/I:N/A:C)

Published

10/21/2024

Created

12/14/2024

Added

12/12/2024

Modified

01/23/2025

Description

In the Linux kernel, the following vulnerability has been resolved: net: avoid potential underflow in qdisc_pkt_len_init() with UFO After commit 7c6d2ecbda83 ("net: be more gentle about silly gso requests coming from user") virtio_net_hdr_to_skb() had sanity check to detect malicious attempts from user space to cook a bad GSO packet. Then commit cf9acc90c80ec ("net: virtio_net_hdr_to_skb: count transport header in UFO") while fixing one issue, allowed user space to cook a GSO packet with the following characteristic : IPv4 SKB_GSO_UDP, gso_size=3, skb->len = 28. When this packet arrives in qdisc_pkt_len_init(), we end up with hdr_len = 28 (IPv4 header + UDP header), matching skb->len Then the following sets gso_segs to 0 : gso_segs = DIV_ROUND_UP(skb->len - hdr_len, shinfo->gso_size); Then later we set qdisc_skb_cb(skb)->pkt_len to back to zero :/ qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len; This leads to the following crash in fq_codel [1] qdisc_pkt_len_init() is best effort, we only want an estimation of the bytes sent on the wire, not crashing the kernel. This patch is fixing this particular issue, a following one adds more sanity checks for another potential bug. [1] [ 70.724101] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 70.724561] #PF: supervisor read access in kernel mode [ 70.724561] #PF: error_code(0x0000) - not-present page [ 70.724561] PGD 10ac61067 P4D 10ac61067 PUD 107ee2067 PMD 0 [ 70.724561] Oops: Oops: 0000 [#1] SMP NOPTI [ 70.724561] CPU: 11 UID: 0 PID: 2163 Comm: b358537762 Not tainted 6.11.0-virtme #991 [ 70.724561] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 70.724561] RIP: 0010:fq_codel_enqueue (net/sched/sch_fq_codel.c:120 net/sched/sch_fq_codel.c:168 net/sched/sch_fq_codel.c:230) sch_fq_codel [ 70.724561] Code: 24 08 49 c1 e1 06 44 89 7c 24 18 45 31 ed 45 31 c0 31 ff 89 44 24 14 4c 03 8b 90 01 00 00 eb 04 39 ca 73 37 4d 8b 39 83 c7 01 <49> 8b 17 49 89 11 41 8b 57 28 45 8b 5f 34 49 c7 07 00 00 00 00 49 All code ======== 0:24 08and$0x8,%al 2:49 c1 e1 06shl$0x6,%r9 6:44 89 7c 24 18 mov%r15d,0x18(%rsp) b:45 31 ed xor%r13d,%r13d e:45 31 c0 xor%r8d,%r8d 11:31 ffxor%edi,%edi 13:89 44 24 14mov%eax,0x14(%rsp) 17:4c 03 8b 90 01 00 00 add0x190(%rbx),%r9 1e:eb 04jmp0x24 20:39 cacmp%ecx,%edx 22:73 37jae0x5b 24:4d 8b 39 mov(%r9),%r15 27:83 c7 01 add$0x1,%edi 2a:*49 8b 17 mov(%r15),%rdx<-- trapping instruction 2d:49 89 11 mov%rdx,(%r9) 30:41 8b 57 28mov0x28(%r15),%edx 34:45 8b 5f 34mov0x34(%r15),%r11d 38:49 c7 07 00 00 00 00 movq $0x0,(%r15) 3f:49 rex.WB Code starting with the faulting instruction =========================================== 0:49 8b 17 mov(%r15),%rdx 3:49 89 11 mov%rdx,(%r9) 6:41 8b 57 28mov0x28(%r15),%edx a:45 8b 5f 34mov0x34(%r15),%r11d e:49 c7 07 00 00 00 00 movq $0x0,(%r15) 15:49 rex.WB [ 70.724561] RSP: 0018:ffff95ae85e6fb90 EFLAGS: 00000202 [ 70.724561] RAX: 0000000002000000 RBX: ffff95ae841de000 RCX: 0000000000000000 [ 70.724561] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001 [ 70.724561] RBP: ffff95ae85e6fbf8 R08: 0000000000000000 R09: ffff95b710a30000 [ 70.724561] R10: 0000000000000000 R11: bdf289445ce31881 R12: ffff95ae85e6fc58 [ 70.724561] R13: 0000000000000000 R14: 0000000000000040 R15: 0000000000000000 [ 70.724561] FS:000000002c5c1380(0000) GS:ffff95bd7fcc0000(0000) knlGS:0000000000000000 [ 70.724561] CS:0010 DS: 0000 ES: 0000 C ---truncated---

Solution(s)

• oracle-linux-upgrade-kernel
• oracle-linux-upgrade-kernel-uek

References

• https://attackerkb.com/topics/cve-2024-49949
• CVE - 2024-49949
• ELSA-2024-10939
• ELSA-2024-10943
• ELSA-2024-12884