{"id":"DEBIAN-CVE-2026-98547","details":"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 \u003c= 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 \u003e= 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-\u003einterval_ktime = ms_to_ktime(prb_calc_retire_blk_tmo(...));         hrtimer_start(&p1-\u003eretire_blk_timer, p1-\u003einterval_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 \u003c 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.","modified":"2026-10-19T05:00:26.299201640Z","published":"2026-10-18T17:47:29.234434852Z","upstream":["CVE-2026-98547"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-98547"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.190-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.187-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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