CVE-2026-23343

Description

In the Linux kernel, the following vulnerability has been resolved: xdp: produce a warning when calculated tailroom is negative Many ethernet drivers report xdp Rx queue frag size as being the same as DMA write size. However, the only user of this field, namely bpf_xdp_frags_increase_tail(), clearly expects a truesize. Such difference leads to unspecific memory corruption issues under certain circumstances, e.g. in ixgbevf maximum DMA write size is 3 KB, so when running xskxceiver's XDP_ADJUST_TAIL_GROW_MULTI_BUFF, 6K packet fully uses all DMA-writable space in 2 buffers. This would be fine, if only rxq->frag_size was properly set to 4K, but value of 3K results in a negative tailroom, because there is a non-zero page offset. We are supposed to return -EINVAL and be done with it in such case, but due to tailroom being stored as an unsigned int, it is reported to be somewhere near UINT_MAX, resulting in a tail being grown, even if the requested offset is too much (it is around 2K in the abovementioned test). This later leads to all kinds of unspecific calltraces. [ 7340.337579] xskxceiver[1440]: segfault at 1da718 ip 00007f4161aeac9d sp 00007f41615a6a00 error 6 [ 7340.338040] xskxceiver[1441]: segfault at 7f410000000b ip 00000000004042b5 sp 00007f415bffecf0 error 4 [ 7340.338179] in libc.so.6[61c9d,7f4161aaf000+160000] [ 7340.339230] in xskxceiver[42b5,400000+69000] [ 7340.340300] likely on CPU 6 (core 0, socket 6) [ 7340.340302] Code: ff ff 01 e9 f4 fe ff ff 0f 1f 44 00 00 4c 39 f0 74 73 31 c0 ba 01 00 00 00 f0 0f b1 17 0f 85 ba 00 00 00 49 8b 87 88 00 00 00 <4c> 89 70 08 eb cc 0f 1f 44 00 00 48 8d bd f0 fe ff ff 89 85 ec fe [ 7340.340888] likely on CPU 3 (core 0, socket 3) [ 7340.345088] Code: 00 00 00 ba 00 00 00 00 be 00 00 00 00 89 c7 e8 31 ca ff ff 89 45 ec 8b 45 ec 85 c0 78 07 b8 00 00 00 00 eb 46 e8 0b c8 ff ff <8b> 00 83 f8 69 74 24 e8 ff c7 ff ff 8b 00 83 f8 0b 74 18 e8 f3 c7 [ 7340.404334] Oops: general protection fault, probably for non-canonical address 0x6d255010bdffc: 0000 [#1] SMP NOPTI [ 7340.405972] CPU: 7 UID: 0 PID: 1439 Comm: xskxceiver Not tainted 6.19.0-rc1+ #21 PREEMPT(lazy) [ 7340.408006] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-5.fc42 04/01/2014 [ 7340.409716] RIP: 0010:lookup_swap_cgroup_id+0x44/0x80 [ 7340.410455] Code: 83 f8 1c 73 39 48 ba ff ff ff ff ff ff ff 03 48 8b 04 c5 20 55 fa bd 48 21 d1 48 89 ca 83 e1 01 48 d1 ea c1 e1 04 48 8d 04 90 <8b> 00 48 83 c4 10 d3 e8 c3 cc cc cc cc 31 c0 e9 98 b7 dd 00 48 89 [ 7340.412787] RSP: 0018:ffffcc5c04f7f6d0 EFLAGS: 00010202 [ 7340.413494] RAX: 0006d255010bdffc RBX: ffff891f477895a8 RCX: 0000000000000010 [ 7340.414431] RDX: 0001c17e3fffffff RSI: 00fa070000000000 RDI: 000382fc7fffffff [ 7340.415354] RBP: 00fa070000000000 R08: ffffcc5c04f7f8f8 R09: ffffcc5c04f7f7d0 [ 7340.416283] R10: ffff891f4c1a7000 R11: ffffcc5c04f7f9c8 R12: ffffcc5c04f7f7d0 [ 7340.417218] R13: 03ffffffffffffff R14: 00fa06fffffffe00 R15: ffff891f47789500 [ 7340.418229] FS: 0000000000000000(0000) GS:ffff891ffdfaa000(0000) knlGS:0000000000000000 [ 7340.419489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 7340.420286] CR2: 00007f415bfffd58 CR3: 0000000103f03002 CR4: 0000000000772ef0 [ 7340.421237] PKRU: 55555554 [ 7340.421623] Call Trace: [ 7340.421987] <TASK> [ 7340.422309] ? softleaf_from_pte+0x77/0xa0 [ 7340.422855] swap_pte_batch+0xa7/0x290 [ 7340.423363] zap_nonpresent_ptes.constprop.0.isra.0+0xd1/0x270 [ 7340.424102] zap_pte_range+0x281/0x580 [ 7340.424607] zap_pmd_range.isra.0+0xc9/0x240 [ 7340.425177] unmap_page_range+0x24d/0x420 [ 7340.425714] unmap_vmas+0xa1/0x180 [ 7340.426185] exit_mmap+0xe1/0x3b0 [ 7340.426644] __mmput+0x41/0x150 [ 7340.427098] exit_mm+0xb1/0x110 [ 7340.427539] do_exit+0x1b2/0x460 [ 7340.427992] do_group_exit+0x2d/0xc0 [ 7340.428477] get_signal+0x79d/0x7e0 [ 7340.428957] arch_do_signal_or_restart+0x34/0x100 [ 7340.429571] exit_to_user_mode_loop+0x8e/0x4c0 [ 7340.430159] do_syscall_64+0x188/ ---truncated---

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Specific versions prior to patch)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// PoC simulation of the integer underflow logic in XDP tailroom calculation
// This demonstrates how a driver reporting DMA size instead of truesize leads to vulnerability.

#include <stdio.h>
#include <stdint.h>
#include <limits.h>

void trigger_vulnerability() {
    // Vulnerable scenario: Driver reports 3KB DMA size instead of 4KB Truesize
    unsigned int frag_size = 3072; // 3KB DMA size
    unsigned int page_offset = 200; // Non-zero offset
    unsigned int data_len = 3072;   // Data occupies full DMA space

    // Vulnerable calculation: tailroom = frag_size - data_len - page_offset
    // Expected: 3072 - 3072 - 200 = -200 (Error)
    unsigned int tailroom = frag_size - data_len - page_offset;

    // Check logic: if tailroom is valid, proceed to grow tail (corrupt memory)
    if (tailroom > 0) {
        printf("[+] Exploit Triggered! Calculated tailroom: %u\n", tailroom);
        printf("[+] Bypassed bounds check. Writing to memory...\n");
        // In kernel: this would call __skb_put() causing skb_over_panic
    } else {
        printf("[-] Check passed. No vulnerability triggered.\n");
    }
}

int main() {
    trigger_vulnerability();
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23343
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23343
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23343/
[4] VulDB https://vuldb.com/cve/CVE-2026-23343
[5] https://git.kernel.org/stable/c/01379540452a02bbc52f639d45dd365cd3624efb
[6] https://git.kernel.org/stable/c/8821e857759be9db3cde337ad328b71fe5c8a55f
[7] https://git.kernel.org/stable/c/94b9da7e9f958cb3d115b21eff824ecd8c3217aa
[8] https://git.kernel.org/stable/c/98cd8b4d0b836d3edf70161f40efd9cbb8c8f252
[9] https://git.kernel.org/stable/c/a0fb59f527d03c60b2cd547cfae4a842ad84670f
[10] https://git.kernel.org/stable/c/c7c790a07697148c41e2d03eb28efe132adda749

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23343", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:32.300", "lastModified": "2026-04-23T21:14:13.387", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxdp: produce a warning when calculated tailroom is negative\n\nMany ethernet drivers report xdp Rx queue frag size as being the same as\nDMA write size. However, the only user of this field, namely\nbpf_xdp_frags_increase_tail(), clearly expects a truesize.\n\nSuch difference leads to unspecific memory corruption issues under certain\ncircumstances, e.g. in ixgbevf maximum DMA write size is 3 KB, so when\nrunning xskxceiver's XDP_ADJUST_TAIL_GROW_MULTI_BUFF, 6K packet fully uses\nall DMA-writable space in 2 buffers. This would be fine, if only\nrxq->frag_size was properly set to 4K, but value of 3K results in a\nnegative tailroom, because there is a non-zero page offset.\n\nWe are supposed to return -EINVAL and be done with it in such case, but due\nto tailroom being stored as an unsigned int, it is reported to be somewhere\nnear UINT_MAX, resulting in a tail being grown, even if the requested\noffset is too much (it is around 2K in the abovementioned test). This later\nleads to all kinds of unspecific calltraces.\n\n[ 7340.337579] xskxceiver[1440]: segfault at 1da718 ip 00007f4161aeac9d sp 00007f41615a6a00 error 6\n[ 7340.338040] xskxceiver[1441]: segfault at 7f410000000b ip 00000000004042b5 sp 00007f415bffecf0 error 4\n[ 7340.338179] in libc.so.6[61c9d,7f4161aaf000+160000]\n[ 7340.339230] in xskxceiver[42b5,400000+69000]\n[ 7340.340300] likely on CPU 6 (core 0, socket 6)\n[ 7340.340302] Code: ff ff 01 e9 f4 fe ff ff 0f 1f 44 00 00 4c 39 f0 74 73 31 c0 ba 01 00 00 00 f0 0f b1 17 0f 85 ba 00 00 00 49 8b 87 88 00 00 00 <4c> 89 70 08 eb cc 0f 1f 44 00 00 48 8d bd f0 fe ff ff 89 85 ec fe\n[ 7340.340888] likely on CPU 3 (core 0, socket 3)\n[ 7340.345088] Code: 00 00 00 ba 00 00 00 00 be 00 00 00 00 89 c7 e8 31 ca ff ff 89 45 ec 8b 45 ec 85 c0 78 07 b8 00 00 00 00 eb 46 e8 0b c8 ff ff <8b> 00 83 f8 69 74 24 e8 ff c7 ff ff 8b 00 83 f8 0b 74 18 e8 f3 c7\n[ 7340.404334] Oops: general protection fault, probably for non-canonical address 0x6d255010bdffc: 0000 [#1] SMP NOPTI\n[ 7340.405972] CPU: 7 UID: 0 PID: 1439 Comm: xskxceiver Not tainted 6.19.0-rc1+ #21 PREEMPT(lazy)\n[ 7340.408006] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-5.fc42 04/01/2014\n[ 7340.409716] RIP: 0010:lookup_swap_cgroup_id+0x44/0x80\n[ 7340.410455] Code: 83 f8 1c 73 39 48 ba ff ff ff ff ff ff ff 03 48 8b 04 c5 20 55 fa bd 48 21 d1 48 89 ca 83 e1 01 48 d1 ea c1 e1 04 48 8d 04 90 <8b> 00 48 83 c4 10 d3 e8 c3 cc cc cc cc 31 c0 e9 98 b7 dd 00 48 89\n[ 7340.412787] RSP: 0018:ffffcc5c04f7f6d0 EFLAGS: 00010202\n[ 7340.413494] RAX: 0006d255010bdffc RBX: ffff891f477895a8 RCX: 0000000000000010\n[ 7340.414431] RDX: 0001c17e3fffffff RSI: 00fa070000000000 RDI: 000382fc7fffffff\n[ 7340.415354] RBP: 00fa070000000000 R08: ffffcc5c04f7f8f8 R09: ffffcc5c04f7f7d0\n[ 7340.416283] R10: ffff891f4c1a7000 R11: ffffcc5c04f7f9c8 R12: ffffcc5c04f7f7d0\n[ 7340.417218] R13: 03ffffffffffffff R14: 00fa06fffffffe00 R15: ffff891f47789500\n[ 7340.418229] FS: 0000000000000000(0000) GS:ffff891ffdfaa000(0000) knlGS:0000000000000000\n[ 7340.419489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 7340.420286] CR2: 00007f415bfffd58 CR3: 0000000103f03002 CR4: 0000000000772ef0\n[ 7340.421237] PKRU: 55555554\n[ 7340.421623] Call Trace:\n[ 7340.421987] <TASK>\n[ 7340.422309] ? softleaf_from_pte+0x77/0xa0\n[ 7340.422855] swap_pte_batch+0xa7/0x290\n[ 7340.423363] zap_nonpresent_ptes.constprop.0.isra.0+0xd1/0x270\n[ 7340.424102] zap_pte_range+0x281/0x580\n[ 7340.424607] zap_pmd_range.isra.0+0xc9/0x240\n[ 7340.425177] unmap_page_range+0x24d/0x420\n[ 7340.425714] unmap_vmas+0xa1/0x180\n[ 7340.426185] exit_mmap+0xe1/0x3b0\n[ 7340.426644] __mmput+0x41/0x150\n[ 7340.427098] exit_mm+0xb1/0x110\n[ 7340.427539] do_exit+0x1b2/0x460\n[ 7340.427992] do_group_exit+0x2d/0xc0\n[ 7340.428477] get_signal+0x79d/0x7e0\n[ 7340.428957] arch_do_signal_or_restart+0x34/0x100\n[ 7340.429571] exit_to_user_mode_loop+0x8e/0x4c0\n[ 7340.430159] do_syscall_64+0x188/\n---truncated---"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch ... (truncated)