DEBIAN-CVE-2026-23327

In the Linux kernel, the following vulnerability has been resolved:  cxl/mbox: validate payload size before accessing contents in cxlpayloadfromuserallowed()  cxlpayloadfromuserallowed() casts and dereferences the input payload without first verifying its size. When a raw mailbox command is sent with an undersized payload (ie: 1 byte for CXLMBOXOPCLEARLOG, which expects a 16-byte UUID), uuidequal() reads past the allocated buffer, triggering a KASAN splat:  BUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683 Read of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258  CPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Call Trace:  <TASK>  dumpstack lib/dumpstack.c:94 [inline]  dumpstacklvl+0xab/0xe0 lib/dumpstack.c:120  printaddressdescription mm/kasan/report.c:378 [inline]  printreport+0xce/0x650 mm/kasan/report.c:482  kasanreport+0xce/0x100 mm/kasan/report.c:595  memcmp+0x176/0x1d0 lib/string.c:683  uuidequal include/linux/uuid.h:73 [inline]  cxlpayloadfromuserallowed drivers/cxl/core/mbox.c:345 [inline]  cxlmboxcmdctor drivers/cxl/core/mbox.c:368 [inline]  cxlvalidatecmdfromuser drivers/cxl/core/mbox.c:522 [inline]  cxlsendcmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643  cxlmemdevioctl drivers/cxl/core/memdev.c:698 [inline]  cxlmemdevioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713  vfsioctl fs/ioctl.c:51 [inline]  dosysioctl fs/ioctl.c:597 [inline]  sesysioctl fs/ioctl.c:583 [inline]  x64sysioctl+0x18e/0x210 fs/ioctl.c:583  dosyscallx64 arch/x86/entry/syscall64.c:63 [inline]  dosyscall64+0xa8/0x330 arch/x86/entry/syscall64.c:94  entrySYSCALL64afterhwframe+0x77/0x7f RIP: 0033:0x7fdaf331ba79 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIGRAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79 RDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003 RBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768  </TASK>  Add 'insize' parameter to cxlpayloadfromuser_allowed() and validate the payload is large enough.