From: Davidlohr Bueso Date: Fri, 20 Feb 2026 00:16:17 +0000 (-0800) Subject: cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_al... X-Git-Tag: ceph-for-7.0-rc4~80^2~2 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=60b5d1f68338aff2c5af0113f04aefa7169c50c2;p=ceph-client.git cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed() cxl_payload_from_user_allowed() 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 CXL_MBOX_OP_CLEAR_LOG, which expects a 16-byte UUID), uuid_equal() 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: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xce/0x650 mm/kasan/report.c:482 kasan_report+0xce/0x100 mm/kasan/report.c:595 memcmp+0x176/0x1d0 lib/string.c:683 uuid_equal include/linux/uuid.h:73 [inline] cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline] cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline] cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline] cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643 __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline] cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+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 ORIG_RAX: 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 Add 'in_size' parameter to cxl_payload_from_user_allowed() and validate the payload is large enough. Fixes: 6179045ccc0c ("cxl/mbox: Block immediate mode in SET_PARTITION_INFO command") Fixes: 206f9fa9d555 ("cxl/mbox: Add Clear Log mailbox command") Signed-off-by: Davidlohr Bueso Reviewed-by: Alison Schofield Reviewed-by: Dave Jiang Link: https://patch.msgid.link/20260220001618.963490-2-dave@stgolabs.net Signed-off-by: Dave Jiang --- diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index fa6dd0c94656..e7a6452bf544 100644 --- a/drivers/cxl/core/mbox.c +++ b/drivers/cxl/core/mbox.c @@ -311,6 +311,7 @@ static bool cxl_mem_raw_command_allowed(u16 opcode) * cxl_payload_from_user_allowed() - Check contents of in_payload. * @opcode: The mailbox command opcode. * @payload_in: Pointer to the input payload passed in from user space. + * @in_size: Size of @payload_in in bytes. * * Return: * * true - payload_in passes check for @opcode. @@ -325,12 +326,15 @@ static bool cxl_mem_raw_command_allowed(u16 opcode) * * The specific checks are determined by the opcode. */ -static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in) +static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in, + size_t in_size) { switch (opcode) { case CXL_MBOX_OP_SET_PARTITION_INFO: { struct cxl_mbox_set_partition_info *pi = payload_in; + if (in_size < sizeof(*pi)) + return false; if (pi->flags & CXL_SET_PARTITION_IMMEDIATE_FLAG) return false; break; @@ -338,6 +342,8 @@ static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in) case CXL_MBOX_OP_CLEAR_LOG: { const uuid_t *uuid = (uuid_t *)payload_in; + if (in_size < sizeof(uuid_t)) + return false; /* * Restrict the ‘Clear log’ action to only apply to * Vendor debug logs. @@ -365,7 +371,8 @@ static int cxl_mbox_cmd_ctor(struct cxl_mbox_cmd *mbox_cmd, if (IS_ERR(mbox_cmd->payload_in)) return PTR_ERR(mbox_cmd->payload_in); - if (!cxl_payload_from_user_allowed(opcode, mbox_cmd->payload_in)) { + if (!cxl_payload_from_user_allowed(opcode, mbox_cmd->payload_in, + in_size)) { dev_dbg(cxl_mbox->host, "%s: input payload not allowed\n", cxl_mem_opcode_to_name(opcode)); kvfree(mbox_cmd->payload_in);