Heimdall Security Logo

CVE-2026-98547

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <3.2, <=6.12.*, 6.18.55, <6279211e7d2456ecd195d236c9ee5e5c6fa5a17a, <56d82862a0a243ac14ba11b6d7b57ddc2d064b95, 0, <b2bcc6a254d6f27823a56787668ae4ee8cdb6e71, <02afd75649a4e001031ed82153a5c39312ec0737, 6.12.112, 5.10.271, 6.6.158, <=5.10.*, <=6.6.*, 6.1.189, f6fb8f100b807378fda19e83e5ac6828b638603a, <=6.18.*, 5.15.222, 3.2, <be1aacff399d519cc48d6b34354a54dd79041140, <218a944b9e035d4b47d59c69af6ca13319da15fb, <=7.2.*, <297acc571d5813db76b147c745b91031d5f9c960, 7.2.9, <=*, <=5.15.*, <eb5b3838b9200dac04bfe33483db0ee8287456fb, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: af_packet: fix integer overflow in prb_calc_retire_blk_tmo() prb_calc_retire_blk_tmo() computes in 32-bit int arithmetic: mbits = (blk_size_in_bytes * 8) / (1024 * 1024); If I'm reading the validation right, tp_block_size is user controlled and packet_set_ring() only rejects values that are <= 0 as int or not page aligned, so a 256MiB block goes right through (and alloc_one_pg_vec_page() even has a vzalloc fallback for it). 0x10000000 * 8 wraps to INT_MIN, and on a NIC reporting 1 Gbps (div == 1) the function ends up returning -2047. The condition is actually (8 * size) mod 2^32 >= 2^31 && div == 1, so the trigger set is [256,512), [768,1024), [1280,1536) and [1792,2048) MiB. Other sizes wrap to non-negative values and faster links divide the unsigned value back below 2^31, which is why this doesn't blow up for everyone. What makes it fatal is what happens next in init_prb_bdqc(): p1->interval_ktime = ms_to_ktime(prb_calc_retire_blk_tmo(...)); hrtimer_start(&p1->retire_blk_timer, p1->interval_ktime, HRTIMER_MODE_REL_SOFT); A negative relative timeout expires immediately. The callback unconditionally returns HRTIMER_RESTART, and hrtimer_forward() turns the negative interval into hrtimer_resolution: if (interval < hrtimer_resolution) interval = hrtimer_resolution; So the SOFT timer re-fires at the maximum rate forever, holding sk_receive_queue.lock each pass. One CPU spins in softirq until the socket is closed. Repeat with more rings and the machine is gone. The overflow itself is ancient - it was introduced together with TPACKET_V3 in f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation."). Its effect prior to f7460d2989fa ("net: af_packet: Use hrtimer to do the retire operation", v6.18) was not as clear-cut, though: the return value was stored into an unsigned short retire_blk_tov, so a negative result was truncated, and a 0-jiffy delay loop could be programmed as well. Neither is nearly as detrimental as the immediate maximum-rate spin the hrtimer conversion turned it into. (Unrelated to CVE-2019-20812 - that one was the ethtool failure path returning 0, which now returns DEFAULT_PRB_RETIRE_TOV.) Reproducer, needs CAP_NET_RAW (a --network host container has it by default) and a 1 Gbps NIC (QEMU e1000 works): int fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); bind(fd, ...); int v = TPACKET_V3; setsockopt(fd, SOL_PACKET, PACKET_VERSION, &v, sizeof(v)); struct tpacket_req3 req = { .tp_block_size = 0x10000000, .tp_block_nr = 1, .tp_frame_size = 2048, .tp_frame_nr = 0x10000000 / 2048, .tp_retire_blk_tov = 0, }; setsockopt(fd, SOL_PACKET, PACKET_RX_RING, &req, sizeof(req)); Compute in 64 bits instead. The operands are already bounded by the existing validation, so nothing else changes. If you'd prefer a different fix, just say so and I'll respin.

Gravité et risque d'exploitation

CVE-2026-98547 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.21 %, ce qui la place devant 10.6 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <3.2, <=6.12.*, 6.18.55, <6279211e7d2456ecd195d236c9ee5e5c6fa5a17a, <56d82862a0a243ac14ba11b6d7b57ddc2d064b95, 0, <b2bcc6a254d6f27823a56787668ae4ee8cdb6e71, <02afd75649a4e001031ed82153a5c39312ec0737, 6.12.112, 5.10.271, 6.6.158, <=5.10.*, <=6.6.*, 6.1.189, f6fb8f100b807378fda19e83e5ac6828b638603a, <=6.18.*, 5.15.222, 3.2, <be1aacff399d519cc48d6b34354a54dd79041140, <218a944b9e035d4b47d59c69af6ca13319da15fb, <=7.2.*, <297acc571d5813db76b147c745b91031d5f9c960, 7.2.9, <=*, <=5.15.*, <eb5b3838b9200dac04bfe33483db0ee8287456fb, 7.3) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

Rechercher une autre CVE