{ "schema_version": "1.6.1", "id": "RPI-CVE-2023-53726", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2023-53726" ], "published": "2025-10-22T13:24:27Z", "summary": "arm64: csum: Fix OoB access in IP checksum code for negative lengths", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: csum: Fix OoB access in IP checksum code for negative lengths\n\nAlthough commit c2c24edb1d9c (\"arm64: csum: Fix pathological zero-length\ncalls\") added an early return for zero-length input, syzkaller has\npopped up with an example of a _negative_ length which causes an\nundefined shift and an out-of-bounds read:\n\n | BUG: KASAN: slab-out-of-bounds in do_csum+0x44/0x254 arch/arm64/lib/csum.c:39\n | Read of size 4294966928 at addr ffff0000d7ac0170 by task syz-executor412/5975\n |\n | CPU: 0 PID: 5975 Comm: syz-executor412 Not tainted 6.4.0-rc4-syzkaller-g908f31f2a05b #0\n | Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023\n | Call trace:\n | dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233\n | show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240\n | __dump_stack lib/dump_stack.c:88 [inline]\n | dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106\n | print_address_description mm/kasan/report.c:351 [inline]\n | print_report+0x174/0x514 mm/kasan/report.c:462\n | kasan_report+0xd4/0x130 mm/kasan/report.c:572\n | kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:187\n | __kasan_check_read+0x20/0x30 mm/kasan/shadow.c:31\n | do_csum+0x44/0x254 arch/arm64/lib/csum.c:39\n | csum_partial+0x30/0x58 lib/checksum.c:128\n | gso_make_checksum include/linux/skbuff.h:4928 [inline]\n | __udp_gso_segment+0xaf4/0x1bc4 net/ipv4/udp_offload.c:332\n | udp6_ufo_fragment+0x540/0xca0 net/ipv6/udp_offload.c:47\n | ipv6_gso_segment+0x5cc/0x1760 net/ipv6/ip6_offload.c:119\n | skb_mac_gso_segment+0x2b4/0x5b0 net/core/gro.c:141\n | __skb_gso_segment+0x250/0x3d0 net/core/dev.c:3401\n | skb_gso_segment include/linux/netdevice.h:4859 [inline]\n | validate_xmit_skb+0x364/0xdbc net/core/dev.c:3659\n | validate_xmit_skb_list+0x94/0x130 net/core/dev.c:3709\n | sch_direct_xmit+0xe8/0x548 net/sched/sch_generic.c:327\n | __dev_xmit_skb net/core/dev.c:3805 [inline]\n | __dev_queue_xmit+0x147c/0x3318 net/core/dev.c:4210\n | dev_queue_xmit include/linux/netdevice.h:3085 [inline]\n | packet_xmit+0x6c/0x318 net/packet/af_packet.c:276\n | packet_snd net/packet/af_packet.c:3081 [inline]\n | packet_sendmsg+0x376c/0x4c98 net/packet/af_packet.c:3113\n | sock_sendmsg_nosec net/socket.c:724 [inline]\n | sock_sendmsg net/socket.c:747 [inline]\n | __sys_sendto+0x3b4/0x538 net/socket.c:2144\n\nExtend the early return to reject negative lengths as well, aligning our\nimplementation with the generic code in lib/checksum.c", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v8", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2023-53726" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5a85727239a23de1cc8d93985f1056308128f3e2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/9a43563cfd6b9200ff2f76b3f9fcdcb217ceb523" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ba0b46166b8e547024d02345a68b747841931ad2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a5ad2f87d8e74e351d3f500ad9d5b3a5653e1c6f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/fcdf904e866de0e3715835e50409fda3b2590527" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8bd795fedb8450ecbef18eeadbd23ed8fc7630f5" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:24:39Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.1, "cvss_v3_severity": "High", "scenario": "AV:L - The trigger is a local `sendmsg()`/`sendto()` on an AF_PACKET socket with a crafted virtio_net_hdr, driving the local TX GSO segmentation path into `gso_make_checksum()` with a negative length. No remote peer input reaches `do_csum()` with a negative length.\nAC:L - The attacker fully controls `csum_start`, `csum_offset` and `gso_size` in the virtio_net_hdr and thus deterministically produces the negative `plen`; there is no race, no memory-layout dependency, and no reliance on unusual configuration for the underlying arm64 kernel to hit the bad path.\nPR:L - AF_PACKET socket creation checks `ns_capable(net->user_ns, CAP_NET_RAW)`, so an unprivileged user obtains it with `unshare -Urn`, which also confers CAP_NET_ADMIN in that netns to disable offloads and force software GSO segmentation.\nUI:N - The attacker triggers the whole sequence from its own process with a socket and a single send; no victim action or cooperation is involved.\nS:U - The faulty read and the undefined shift both occur within kernel context on behalf of the calling task, with no crossing of a VM, IOMMU, or other security-authority boundary.\nC:H - The fix addresses an out-of-bounds read in the checksum primitive with an attacker-influenced negative length, and the resulting checksum is emitted in the outgoing packet, exposing a function of memory outside the intended range; sufficiently negative lengths wrap `len + offset - 8` positive and let the main loop walk arbitrary kernel memory.\nI:N - `do_csum()` performs only loads; the sole downstream effect is a bogus checksum value written into the attacker's own outgoing packet, with no modification of kernel memory or other principals' data.\nA:H - The condition is reported as a KASAN slab-out-of-bounds BUG, which panics kernels built with KASAN or running `panic_on_warn`/`kasan.fault=panic`, and an unbounded negative length drives the 64-byte-stride loop off the end of the object into unmapped memory, oopsing the kernel." } } }