{"id":70171,"date":"2025-09-15T18:32:12","date_gmt":"2025-09-15T15:02:12","guid":{"rendered":"https:\/\/afaghhosting.net\/blog\/cve-2023-53240-xsk-check-iff_up-earlier-in-tx-path\/"},"modified":"2025-09-15T18:32:12","modified_gmt":"2025-09-15T15:02:12","slug":"cve-2023-53240-xsk-check-iff_up-earlier-in-tx-path","status":"publish","type":"post","link":"https:\/\/afaghhosting.net\/blog\/cve-2023-53240-xsk-check-iff_up-earlier-in-tx-path\/","title":{"rendered":"CVE-2023-53240 – xsk: check IFF_UP earlier in Tx path"},"content":{"rendered":"

CVE ID : <\/strong>CVE-2023-53240
\n
\nPublished : <\/strong> Sept. 15, 2025, 2:22 p.m. | 32\u00a0minutes ago
\n
\nDescription : <\/strong>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n

xsk: check IFF_UP earlier in Tx path<\/p>\n

Xsk Tx can be triggered via either sendmsg() or poll() syscalls. These
\ntwo paths share a call to common function xsk_xmit() which has two
\nsanity checks within. A pseudo code example to show the two paths:<\/p>\n

__xsk_sendmsg() : xsk_poll():
\nif (unlikely(!xsk_is_bound(xs))) if (unlikely(!xsk_is_bound(xs)))
\n return -ENXIO; return mask;
\nif (unlikely(need_wait)) (…)
\n return -EOPNOTSUPP; xsk_xmit()
\nmark napi id
\n(…)
\nxsk_xmit()<\/p>\n

xsk_xmit():
\nif (unlikely(!(xs->dev->flags & IFF_UP)))
\n\treturn -ENETDOWN;
\nif (unlikely(!xs->tx))
\n\treturn -ENOBUFS;<\/p>\n

As it can be observed above, in sendmsg() napi id can be marked on
\ninterface that was not brought up and this causes a NULL ptr
\ndereference:<\/p>\n[31757.505631] BUG: kernel NULL pointer dereference, address: 0000000000000018
\n[31757.512710] #PF: supervisor read access in kernel mode
\n[31757.517936] #PF: error_code(0x0000) – not-present page
\n[31757.523149] PGD 0 P4D 0
\n[31757.525726] Oops: 0000 [#1] PREEMPT SMP NOPTI
\n[31757.530154] CPU: 26 PID: 95641 Comm: xdpsock Not tainted 6.2.0-rc5+ #40
\n[31757.536871] Hardware name: Intel Corporation S2600WFT\/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03\/19\/2019
\n[31757.547457] RIP: 0010:xsk_sendmsg+0xde\/0x180
\n[31757.551799] Code: 00 75 a2 48 8b 00 a8 04 75 9b 84 d2 74 69 8b 85 14 01 00 00 85 c0 75 1b 48 8b 85 28 03 00 00 48 8b 80 98 00 00 00 48 8b 40 20 40 18 89 85 14 01 00 00 8b bd 14 01 00 00 81 ff 00 01 00 00 0f
\n[31757.570840] RSP: 0018:ffffc90034f27dc0 EFLAGS: 00010246
\n[31757.576143] RAX: 0000000000000000 RBX: ffffc90034f27e18 RCX: 0000000000000000
\n[31757.583389] RDX: 0000000000000001 RSI: ffffc90034f27e18 RDI: ffff88984cf3c100
\n[31757.590631] RBP: ffff88984714a800 R08: ffff88984714a800 R09: 0000000000000000
\n[31757.597877] R10: 0000000000000001 R11: 0000000000000000 R12: 00000000fffffffa
\n[31757.605123] R13: 0000000000000000 R14: 0000000000000003 R15: 0000000000000000
\n[31757.612364] FS: 00007fb4c5931180(0000) GS:ffff88afdfa00000(0000) knlGS:0000000000000000
\n[31757.620571] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
\n[31757.626406] CR2: 0000000000000018 CR3: 000000184b41c003 CR4: 00000000007706e0
\n[31757.633648] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
\n[31757.640894] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
\n[31757.648139] PKRU: 55555554
\n[31757.650894] Call Trace:
\n[31757.653385]\n[31757.655524] sock_sendmsg+0x8f\/0xa0
\n[31757.659077] ? sockfd_lookup_light+0x12\/0x70
\n[31757.663416] __sys_sendto+0xfc\/0x170
\n[31757.667051] ? do_sched_setscheduler+0xdb\/0x1b0
\n[31757.671658] __x64_sys_sendto+0x20\/0x30
\n[31757.675557] do_syscall_64+0x38\/0x90
\n[31757.679197] entry_SYSCALL_64_after_hwframe+0x72\/0xdc
\n[31757.687969] Code: 8e f6 ff 44 8b 4c 24 2c 4c 8b 44 24 20 41 89 c4 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 3d 00 f0 ff ff 77 3a 44 89 e7 48 89 44 24 08 e8 b5 8e f6 ff 48
\n[31757.707007] RSP: 002b:00007ffd49c73c70 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
\n[31757.714694] RAX: ffffffffffffffda RBX: 000055a996565380 RCX: 00007fb4c5727c16
\n[31757.721939] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
\n[31757.729184] RBP: 0000000000000040 R08: 0000000000000000 R09: 0000000000000000
\n[31757.736429] R10: 0000000000000040 R11: 0000000000000293 R12: 0000000000000000
\n[31757.743673] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
\n[31757.754940] <\/p>\n

To fix this, let’s make xsk_xmit a function that will be responsible for
\ngeneric Tx, where RCU is handled accordingly and pull out sanity checks
\nand xs->zc handling. Populate sanity checks to __xsk_sendmsg() and
\nxsk_poll().
\n
\nSeverity:<\/strong> 0.0 | NA
\n
\nVisit the link for more details, such as CVSS details, affected products, timeline, and more…<\/p>\n","protected":false},"excerpt":{"rendered":"

CVE ID : CVE-2023-53240 Published : Sept. 15, 2025, 2:22 p.m. | 32\u00a0minutes ago Description : In the Linux kernel, the following vulnerability has been resolved: xsk: check IFF_UP earlier in Tx path Xsk Tx can be triggered via either sendmsg() or poll() syscalls. These two paths share a call to common function xsk_xmit() which …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-70171","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/70171","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=70171"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/70171\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=70171"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=70171"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=70171"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}