In the Linux kernel, the following vulnerability has been resolved:
kcm: Fix memory leak in error path of kcm_sendmsg()
syzbot reported a memory leak like below:
BUG: memory leak unreferenced object 0xffff88810b088c00 (size 240): comm "syz-executor186", pid 5012, jiffies 4294943306 (age 13.680s) hex dump (first 32 bytes): 00 89 08 0b 81 88 ff ff 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff83e5d5ff>] __alloc_skb+0x1ef/0x230 net/core/skbuff.c:634 [<ffffffff84606e59>] alloc_skb include/linux/skbuff.h:1289 [inline] [<ffffffff84606e59>] kcm_sendmsg+0x269/0x1050 net/kcm/kcmsock.c:815 [<ffffffff83e479c6>] sock_sendmsg_nosec net/socket.c:725 [inline] [<ffffffff83e479c6>] sock_sendmsg+0x56/0xb0 net/socket.c:748 [<ffffffff83e47f55>] ____sys_sendmsg+0x365/0x470 net/socket.c:2494 [<ffffffff83e4c389>] ___sys_sendmsg+0xc9/0x130 net/socket.c:2548 [<ffffffff83e4c536>] __sys_sendmsg+0xa6/0x120 net/socket.c:2577 [<ffffffff84ad7bb8>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<ffffffff84ad7bb8>] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 [<ffffffff84c0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
In kcm_sendmsg(), kcm_tx_msg(head)->last_skb is used as a cursor to append newly allocated skbs to 'head'. If some bytes are copied, an error occurred, and jumped to out_error label, 'last_skb' is left unmodified. A later kcm_sendmsg() will use an obsoleted 'last_skb' reference, corrupting the 'head' frag_list and causing the leak.
This patch fixes this issue by properly updating the last allocated skb in 'last_skb'.
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-tools-develUpgrade kernel-debuginfo-common-aarch64Upgrade perfUpgrade kernel-toolsUpgrade python-perfUpgrade kernel-livepatch-5.10.196-185.743Upgrade kernelUpgrade bpftoolUpgrade bpftool-debuginfoUpgrade perf-debuginfoUpgrade kernel-develUpgrade kernel-livepatch-5.15.133-86.144Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfoUpgrade kernel-livepatch-4.14.326-245.539Upgrade kernel-headersUpgrade python-perf-debuginfoUpgrade kernel-tools-debuginfo | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | Dec 29, 2025 | Dec 29, 2025 |
| Ubuntu | — | Upgrade linux-gcp-5.4Upgrade linux-riscv-5.15Upgrade linux-raspi-5.4Upgrade linux-lowlatency-hwe-5.15Upgrade linux-gcpUpgrade linux-oracle-5.4Upgrade linux-bluefieldUpgrade linux-nvidia-tegraUpgrade linux-nvidia-tegra-5.15Upgrade linux-ibm-5.4Upgrade linux-fipsUpgrade linux-awsUpgrade linux-gkeUpgrade linux-lowlatencyUpgrade linuxUpgrade linux-intel-iot-realtimeUpgrade linux-raspiUpgrade linux-aws-5.15Upgrade linux-ibm-5.15Upgrade linux-aws-5.4Upgrade linux-oracle-5.15Upgrade linux-xilinx-zynqmpUpgrade linux-nvidiaUpgrade linux-nvidia-tegra-igxUpgrade linux-hwe-5.4Upgrade linux-kvmUpgrade linux-azureUpgrade linux-aws-fipsUpgrade linux-gcp-5.15Upgrade linux-realtimeUpgrade linux-iotUpgrade linux-hwe-5.15Upgrade linux-azure-5.15Upgrade linux-gkeopUpgrade linux-azure-5.4Upgrade linux-intel-iotg-5.15Upgrade linux-oracleUpgrade linux-azure-fipsUpgrade linux-intel-iotgUpgrade linux-gcp-fipsUpgrade linux-ibm | Jan 6, 2026 | Dec 24, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 24, 2025 |
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