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bb9b0e46b8
One-element and zero-length arrays are deprecated. Replace one-element array in struct vmtransfer_page_packet_header with flexible-array member. This change fixes below warning: [ 2.593788] ================================================================================ [ 2.593908] UBSAN: array-index-out-of-bounds in drivers/net/hyperv/netvsc.c:1445:41 [ 2.593989] index 1 is out of range for type 'vmtransfer_page_range [1]' [ 2.594049] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.5.0-rc4-next-20230803+ #1 [ 2.594114] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 04/20/2023 [ 2.594121] Call Trace: [ 2.594126] <IRQ> [ 2.594133] dump_stack_lvl+0x4c/0x70 [ 2.594154] dump_stack+0x14/0x20 [ 2.594162] __ubsan_handle_out_of_bounds+0xa6/0xf0 [ 2.594224] netvsc_poll+0xc01/0xc90 [hv_netvsc] [ 2.594258] __napi_poll+0x30/0x1e0 [ 2.594320] net_rx_action+0x194/0x2f0 [ 2.594333] __do_softirq+0xde/0x31e [ 2.594345] __irq_exit_rcu+0x6b/0x90 [ 2.594357] irq_exit_rcu+0x12/0x20 [ 2.594366] sysvec_hyperv_callback+0x84/0x90 [ 2.594376] </IRQ> [ 2.594379] <TASK> [ 2.594383] asm_sysvec_hyperv_callback+0x1f/0x30 [ 2.594394] RIP: 0010:pv_native_safe_halt+0xf/0x20 [ 2.594452] Code: 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 05 35 3f 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 [ 2.594459] RSP: 0018:ffffb841c00d3e88 EFLAGS: 00000256 [ 2.594469] RAX: ffff9d18c326f4a0 RBX: ffff9d18c031df40 RCX: 4000000000000000 [ 2.594475] RDX: 0000000000000001 RSI: 0000000000000082 RDI: 00000000000268dc [ 2.594481] RBP: ffffb841c00d3e90 R08: 00000066a171109b R09: 00000000d33d2600 [ 2.594486] R10: 000000009a41bf00 R11: 0000000000000000 R12: 0000000000000001 [ 2.594491] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 2.594501] ? ct_kernel_exit.constprop.0+0x7d/0x90 [ 2.594513] ? default_idle+0xd/0x20 [ 2.594523] arch_cpu_idle+0xd/0x20 [ 2.594532] default_idle_call+0x30/0xe0 [ 2.594542] do_idle+0x200/0x240 [ 2.594553] ? complete+0x71/0x80 [ 2.594613] cpu_startup_entry+0x24/0x30 [ 2.594624] start_secondary+0x12d/0x160 [ 2.594634] secondary_startup_64_no_verify+0x17e/0x18b [ 2.594649] </TASK> [ 2.594656] ================================================================================ With this change the structure size is reduced by 8 bytes, below is the pahole output. struct vmtransfer_page_packet_header { struct vmpacket_descriptor d; /* 0 16 */ u16 xfer_pageset_id; /* 16 2 */ u8 sender_owns_set; /* 18 1 */ u8 reserved; /* 19 1 */ u32 range_cnt; /* 20 4 */ struct vmtransfer_page_range ranges[]; /* 24 0 */ /* size: 24, cachelines: 1, members: 6 */ /* last cacheline: 24 bytes */ }; The validation code in the netvsc driver is affected by changing the struct size, but the effects have been examined and have been determined to be appropriate. Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Wei Liu <wei.liu@kernel.org> Link: https://lore.kernel.org/r/1692160478-18469-1-git-send-email-ssengar@linux.microsoft.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.