> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Guangshuo Li
> Sent: Tuesday, November 4, 2025 9:28 AM
> To: Jesse Brandeburg <[email protected]>; Nguyen, Anthony L
> <[email protected]>; David S. Miller <[email protected]>;
> Jakub Kicinski <[email protected]>; Paolo Abeni <[email protected]>;
> Jeff Kirsher <[email protected]>; Florian Westphal
> <[email protected]>; [email protected];
> [email protected]; [email protected]
> Cc: Guangshuo Li <[email protected]>; [email protected]
> Subject: [Intel-wired-lan] [PATCH] e1000: fix OOB in
> e1000_tbi_should_accept()
>
> In e1000_tbi_should_accept() we read the last byte of the frame via
> 'data[length - 1]' to evaluate the TBI workaround. If the descriptor-
> reported length is zero or larger than the actual RX buffer size, this
> read goes out of bounds and can hit unrelated slab objects. The issue
> is observed from the NAPI receive path (e1000_clean_rx_irq):
>
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in e1000_tbi_should_accept+0x610/0x790
> Read of size 1 at addr ffff888014114e54 by task sshd/363
>
> CPU: 0 PID: 363 Comm: sshd Not tainted 5.18.0-rc1 #1 Hardware name:
> QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-
> gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace:
> <IRQ>
> dump_stack_lvl+0x5a/0x74
> print_address_description+0x7b/0x440
> print_report+0x101/0x200
> kasan_report+0xc1/0xf0
> e1000_tbi_should_accept+0x610/0x790
> e1000_clean_rx_irq+0xa8c/0x1110
> e1000_clean+0xde2/0x3c10
> __napi_poll+0x98/0x380
> net_rx_action+0x491/0xa20
> __do_softirq+0x2c9/0x61d
> do_softirq+0xd1/0x120
> </IRQ>
> <TASK>
> __local_bh_enable_ip+0xfe/0x130
> ip_finish_output2+0x7d5/0xb00
> __ip_queue_xmit+0xe24/0x1ab0
> __tcp_transmit_skb+0x1bcb/0x3340
> tcp_write_xmit+0x175d/0x6bd0
> __tcp_push_pending_frames+0x7b/0x280
> tcp_sendmsg_locked+0x2e4f/0x32d0
> tcp_sendmsg+0x24/0x40
> sock_write_iter+0x322/0x430
> vfs_write+0x56c/0xa60
> ksys_write+0xd1/0x190
> do_syscall_64+0x43/0x90
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f511b476b10
> Code: 73 01 c3 48 8b 0d 88 d3 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66
> 0f 1f 44 00 00 83 3d f9 2b 2c 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d
> 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 8e 9b 01 00 48 89 04 24
> RSP: 002b:00007ffc9211d4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000004024 RCX: 00007f511b476b10
> RDX: 0000000000004024 RSI: 0000559a9385962c RDI: 0000000000000003
> RBP: 0000559a9383a400 R08: fffffffffffffff0 R09: 0000000000004f00
> R10: 0000000000000070 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffc9211d57f R14: 0000559a9347bde7 R15: 0000000000000003
> </TASK> Allocated by task 1:
> __kasan_krealloc+0x131/0x1c0
> krealloc+0x90/0xc0
> add_sysfs_param+0xcb/0x8a0
> kernel_add_sysfs_param+0x81/0xd4
> param_sysfs_builtin+0x138/0x1a6
> param_sysfs_init+0x57/0x5b
> do_one_initcall+0x104/0x250
> do_initcall_level+0x102/0x132
> do_initcalls+0x46/0x74
> kernel_init_freeable+0x28f/0x393
> kernel_init+0x14/0x1a0
> ret_from_fork+0x22/0x30
> The buggy address belongs to the object at ffff888014114000 which
> belongs to the cache kmalloc-2k of size 2048 The buggy address is
> located 1620 bytes to the right of 2048-byte region
> [ffff888014114000, ffff888014114800] The buggy address belongs to the
> physical page:
> page:ffffea0000504400 refcount:1 mapcount:0 mapping:0000000000000000
> index:0x0 pfn:0x14110
> head:ffffea0000504400 order:3 compound_mapcount:0 compound_pincount:0
> flags: 0x100000000010200(slab|head|node=0|zone=1)
> raw: 0100000000010200 0000000000000000 dead000000000001
> ffff888013442000
> raw: 0000000000000000 0000000000080008 00000001ffffffff
> 0000000000000000 page dumped because: kasan: bad access detected
> ==================================================================
>
> This happens because the TBI check unconditionally dereferences the
> last byte without validating the reported length first:
>
> u8 last_byte = *(data + length - 1);
>
> Fix by rejecting the frame early if the length is zero, or if it
> exceeds
> adapter->rx_buffer_len. This preserves the TBI workaround semantics
> for
> valid frames and prevents touching memory beyond the RX buffer.
>
> Fixes: 2037110c96d5 ("e1000: move tbi workaround code into helper
> function")
> Cc: [email protected]
> Signed-off-by: Guangshuo Li <[email protected]>
> ---
> drivers/net/ethernet/intel/e1000/e1000_main.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c
> b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index 3f5feb55cfba..2d2ed5e2c3c8 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -4090,6 +4090,12 @@ static bool e1000_tbi_should_accept(struct
> e1000_adapter *adapter,
> u8 status, u8 errors,
> u32 length, const u8 *data)
> {
> + /* Guard against OOB on data[length - 1] */
> + if (unlikely(!length))
> + return false;
> + /* Upper bound: length must not exceed rx_buffer_len */
> + if (unlikely(length > adapter->rx_buffer_len))
> + return false;
> struct e1000_hw *hw = &adapter->hw;
> u8 last_byte = *(data + length - 1);
>
> --
> 2.43.0
Reviewed-by: Aleksandr Loktionov <[email protected]>
